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raygreenwood Samba Member
Joined: November 24, 2008 Posts: 21510 Location: Oklahoma City
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Posted: Sun Mar 25, 2018 10:51 pm Post subject: Re: Melling High Volume Oil Pump for Type 4 Motor |
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Oooooh. I could go for a taco plate like that!
There is only one "elastomer" than can do better than the permatex ultra series.....all of which have no issues with oil for 100k miles....especially in thin films. That is viton resin..........well....other than a couple of two part silicones I have recently found......but they run about $150 a pound.
The permatex ultra series only fail in oil.... over long periods....and with immersion from all sides that can get between the film layer and the metal. If its properly applied and cured....thks cannot happen.
The key to using them without failure with hot oil with fuel in it.....is using them thin and letting them cure fully. In the TDS....they are looking at 72 hours curing time in "bead" profile. A minimum of 24 for a thin film.
This presents a maximum of .003" of surface area for exposure to oil surrounding the ports. It takes months for the solvents in fuel to attack what it can reach....which is only .003" in surtace area......AS LONG AS...its fully cured first so that oil cannot reach the flat sides of the film.
This is why it needs to be cured all the way first....and not contacted wet. At the rate the oil will attack it.....it will take about 8 years for the oil to penetrate about .020" into this thin film of only .003" to .005" thick.
This is where ALL of the cursory RTV testing totally screws up. They take a barely cured glob or sheet of the RTV and drop it into a beaker of hot solvent filled oil....and then are amazed that after X hours...it seems softer.
Yet.....a glob of RTV......is not a seal or a gasket.....and the oil has access to all surfaces. Not a useful test.
In motor oil....100% of all elastomers...even certain grades of viton, all vinyls all neoprenes and all nitriles.....fail ...in hot oil immersion tests. It matters how its used....and how its cured.
I have some liquid Viton compound that survives over 2500 hours in jet engine intakes.....that may be a candidate for this type of seal. I didnt get it for this but it could be excellent. Its durometer is 70 A....so it would have to be tested to know what thickness to use as its compression is less.
One of engines I put this type of oil pump seal in....ran almost 130k miles over 6 uears in a 914. When it came out.....after he locked it up on the track .....when we did the autopsy.....the very edge of this sealing area had that classic slightly wrinkled gooey look you eventuqlly get with RTV from fuel attack.....BUT......with only about .020" of lateral penetration outward from the oil pump port...into the film layer of the seal. It was still totally functional.
This is the same effect you get on intake gaskets...with high quality, high temp, oil resistant RTVs....when they are properly applied....AND....properly cured before assembly......they do not fail.....and have temp ranges of 500°F constant. Ray |
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williamM Samba Member
Joined: August 07, 2008 Posts: 4333 Location: southwest Arizona
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Posted: Mon Mar 26, 2018 3:40 am Post subject: Re: Melling High Volume Oil Pump for Type 4 Motor |
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[quote="raygreenwood"][quote="williamM"] I take it this would be for the original assembly.
That is a type 4 Melling in the pictures....not sure what you meant by original assembly.
Quote: |
By that I meant -- to install in a split case - settle the pump in the block, remove 2 studs and bolt it up then install the studs- Just would be leery of tapping in the pump and scraping some of that seal off on installation. |
_________________ some days I get up and just sit and think. Some days I just sit.
opinion untempered by fact is ignorance.
Don't step in any! |
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69BahamaYellow Samba Member
Joined: April 22, 2011 Posts: 536 Location: Talbott, TN
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Posted: Mon Mar 26, 2018 5:02 am Post subject: Re: Melling High Volume Oil Pump for Type 4 Motor |
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This is great stuff, which has led me to do more reading about the Melling pumps and their advantages / disadvantages. So I guess at this point, I'm going to put the Melling pump back in my parts bin and stick with the OEM pump. I never had any issue with my oil pressure light flickering at idle before I tore my motor down and that's running 5W-40 oil in TX heat. My original thinking was that the Melling pump would be an improvement, with the extra volume, but the consensus seems to be that a stock motor needs the stock oil pressure and volume for the oil cooler to properly do it's job, and save the high volume pumps for use with external oil coolers or looser bearing clearances. It appears the Melling is an excellent choice for that, and there are some good ways to cure it's shortcomings.
You would think that the bigger, more powerful type 4 motor would get bigger oil pump gears than it's type 1 predecessor, but unless I'm reading my Bently manual wrong, type 4's have 24mm gears, while type 1's have 26mm. For the engineers to make that kind of change, there must have been a good reason (bigger is not always better).
The OEM pump gears and clearance seem fine on my motor, and I solved my clearance problem with the cam gear bolts, just by screwing the top 2 of 4 M6 studs a little deeper into the pump (I'm talking about the studs in the outer pump housing that hold the 2 pieces of the OEM pump together). The head of those studs protrudes about .015" beyond the nut (fully assembled), so screwing them in a little further, and measuring with the pump to case gasket installed, gave over .040" clearance between the cam gear bolts. Quick question for the experts - what is the torque supposed to be on the 4 M-6 pump bolts? The Bently manual reads as if they are supposed to be 14 ft-lbs, but I believe that's the spec for the 4 M-8 bolts that hold the pump to the engine case. I would think a M-6 should be somewhere in the 8-9 ft-lb range.... |
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raygreenwood Samba Member
Joined: November 24, 2008 Posts: 21510 Location: Oklahoma City
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Posted: Mon Mar 26, 2018 7:26 am Post subject: Re: Melling High Volume Oil Pump for Type 4 Motor |
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[quote="williamM"][quote="raygreenwood"]
williamM wrote: |
I take it this would be for the original assembly.
That is a type 4 Melling in the pictures....not sure what you meant by original assembly.
Quote: |
By that I meant -- to install in a split case - settle the pump in the block, remove 2 studs and bolt it up then install the studs- Just would be leery of tapping in the pump and scraping some of that seal off on installation. |
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Oh...yep.....definatly only for use on a complete disassembly.
Ray |
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raygreenwood Samba Member
Joined: November 24, 2008 Posts: 21510 Location: Oklahoma City
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Posted: Mon Mar 26, 2018 7:44 am Post subject: Re: Melling High Volume Oil Pump for Type 4 Motor |
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69BahamaYellow wrote: |
This is great stuff, which has led me to do more reading about the Melling pumps and their advantages / disadvantages. So I guess at this point, I'm going to put the Melling pump back in my parts bin and stick with the OEM pump. I never had any issue with my oil pressure light flickering at idle before I tore my motor down and that's running 5W-40 oil in TX heat. My original thinking was that the Melling pump would be an improvement, with the extra volume, but the consensus seems to be that a stock motor needs the stock oil pressure and volume for the oil cooler to properly do it's job, and save the high volume pumps for use with external oil coolers or looser bearing clearances. It appears the Melling is an excellent choice for that, and there are some good ways to cure it's shortcomings.
You would think that the bigger, more powerful type 4 motor would get bigger oil pump gears than it's type 1 predecessor, but unless I'm reading my Bently manual wrong, type 4's have 24mm gears, while type 1's have 26mm. For the engineers to make that kind of change, there must have been a good reason (bigger is not always better).
The OEM pump gears and clearance seem fine on my motor, and I solved my clearance problem with the cam gear bolts, just by screwing the top 2 of 4 M6 studs a little deeper into the pump (I'm talking about the studs in the outer pump housing that hold the 2 pieces of the OEM pump together). The head of those studs protrudes about .015" beyond the nut (fully assembled), so screwing them in a little further, and measuring with the pump to case gasket installed, gave over .040" clearance between the cam gear bolts. Quick question for the experts - what is the torque supposed to be on the 4 M-6 pump bolts? The Bently manual reads as if they are supposed to be 14 ft-lbs, but I believe that's the spec for the 4 M-8 bolts that hold the pump to the engine case. I would think a M-6 should be somewhere in the 8-9 ft-lb range.... |
A couple of alarming items.......if you are able to screw the studs into the oil pump deeper.....they are a risk. They should have been bottomed out. It means they were loose and can work loose over time.
You need to pull them.....clean the heck out of them with acetone inside and out....and Loctite them. Also use NEW lockwashers and Loctite on the nuts.
The deal with the oil pump size has nothing to do with engine size. Its how much oil galley volume, length, diameter and bearing area....so how much drag on the oil volume and pressure.....and how much loss through all other sources....and a big part is how the oil is controlled and routed.
The type 4 has better oil routing, larger galley sizes and a little bit better control over pressure. But really the bearing area and galley volume and surface area are not much larger than a type 1. It really does not need a larger pump.
I cannot find a spec for the oil pump inner nuts in any of my books.....but in one of my notebooks I have a note of 8-10 ft lbs/ 96-120 inch lbs.....and I have always safely used that....but have no idea where I got it many years ago.
Ray |
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SGKent Samba Member
Joined: October 30, 2007 Posts: 41031 Location: Citrus Heights CA (Near Sacramento)
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Posted: Mon Mar 26, 2018 8:00 am Post subject: Re: Melling High Volume Oil Pump for Type 4 Motor |
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5 ft pounds is the factory spec (60 inch pounds). You can do 7 or 8 but don't go past that. Use red Loctite on both the cam and oil pump bolts / studs- nuts. The 14 ft lbs is for the 8 mm nuts that hold it to the case. _________________ “Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin |
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SGKent Samba Member
Joined: October 30, 2007 Posts: 41031 Location: Citrus Heights CA (Near Sacramento)
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Posted: Fri May 11, 2018 7:52 pm Post subject: Re: Melling High Volume Oil Pump for Type 4 Motor |
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someone asked about the source of the torque rating on the pumps. Same for automatic as manual.
_________________ “Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin |
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WhirledTraveller Samba Member
Joined: January 09, 2008 Posts: 1399 Location: Cambridge, MA
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Posted: Mon May 14, 2018 7:02 am Post subject: Re: Melling High Volume Oil Pump for Type 4 Motor |
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I used brass .002 shim stock to get my oil pump to fit correctly in the bore. This made a noticeable improvement in the oil pressure and I feel better about it in the engine than RTV although I'm sure if one is as meticulous as ray then it's a perfectly fine mod.
My engine was built with a 26mm Shadek and the engine builder used RTV all around to seal the loose fit. Oil pressure was "shite", flickering at idle, 28 psi or so hot engine at 3500 rpm
Replaced with 30mm O-ringed Gene Berg. Brought the pressure up to 35-36 psi hot engine at 3500 rpm but nearly self destructed the engine when the idle shaft walked.
Replaced with 30mm custom type-IV pump and brass shim stock to get a tight fit. Installed without splitting the case using hot engine and the pump frozen in a freezer.
Pressure is now 40-45 psi at 3500 rpm hot engine. 5w50 oil. This is in my mind exactly correct.
I believe the 10 psi pressure difference between the 30mm Gene Berg and the 30mm Custom pump is partly due to better manufacturing tolerances in the pump itself, but also significantly added to by the better inlet/outlet seal using the brass shim. _________________ 1977 Westy, Automatic. Big Valve heads, CS Cam. |
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orwell84 Samba Member
Joined: May 14, 2007 Posts: 2536 Location: Plattsburgh, New York
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Posted: Tue May 15, 2018 6:00 am Post subject: Re: Melling High Volume Oil Pump for Type 4 Motor |
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WhirledTraveller wrote: |
I used brass .002 shim stock to get my oil pump to fit correctly in the bore. This made a noticeable improvement in the oil pressure and I feel better about it in the engine than RTV although I'm sure if one is as meticulous as ray then it's a perfectly fine mod.
My engine was built with a 26mm Shadek and the engine builder used RTV all around to seal the loose fit. Oil pressure was "shite", flickering at idle, 28 psi or so hot engine at 3500 rpm
Replaced with 30mm O-ringed Gene Berg. Brought the pressure up to 35-36 psi hot engine at 3500 rpm but nearly self destructed the engine when the idle shaft walked.
Replaced with 30mm custom type-IV pump and brass shim stock to get a tight fit. Installed without splitting the case using hot engine and the pump frozen in a freezer.
Pressure is now 40-45 psi at 3500 rpm hot engine. 5w50 oil. This is in my mind exactly correct.
I believe the 10 psi pressure difference between the 30mm Gene Berg and the 30mm Custom pump is partly due to better manufacturing tolerances in the pump itself, but also significantly added to by the better inlet/outlet seal using the brass shim. |
Your oil pressure numbers with the 26mm Shadek pump are very close to mine using the same pump. I have the stock sender plumbed in with a T, so I don't get a flickering oil light, but I did on hot days when using the VDO sensor alone. I have had the same issue with the Shadek pump being a loose fit in the case. I can just pull it out by hand while I was only able to remove the stock pump when I split the case. I recently tightened up a stock pump through lapping. A teacher in the marine engine vocational program where I work made a lapping plate by using another pump face with a fine adhesive backed sand paper applied . Quick and dirty, I know, but it tightened ride up with a little hand lapping. I will revive my thread about this when I am ready to install it. Curious about the 30mm type 4 custom pump you are referring to. I wanted to test whether the poor fit of the Shadek pump was a factor in my low oil pressure at hot temps. If so, I will scare up a couple more used pumps to send to Phil so he has the best shot at making a good one. |
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WhirledTraveller Samba Member
Joined: January 09, 2008 Posts: 1399 Location: Cambridge, MA
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Posted: Tue May 15, 2018 6:07 am Post subject: Re: Melling High Volume Oil Pump for Type 4 Motor |
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The custom pump was, for a time, available from a German machinist who sold them on german ebay one at a time as he made them. As far as I know, he doesn't sell them anymore because it was a hobby for him not a business. It's a true piece of art. Here's a blurry pic:
And with the brass shim, just prior to freezing:
_________________ 1977 Westy, Automatic. Big Valve heads, CS Cam. |
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raygreenwood Samba Member
Joined: November 24, 2008 Posts: 21510 Location: Oklahoma City
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Posted: Tue May 15, 2018 7:42 am Post subject: Re: Melling High Volume Oil Pump for Type 4 Motor |
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WhirledTraveller wrote: |
The custom pump was, for a time, available from a German machinist who sold them on german ebay one at a time as he made them. As far as I know, he doesn't sell them anymore because it was a hobby for him not a business. It's a true piece of art. Here's a blurry pic:
And with the brass shim, just prior to freezing:
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Wow! Very pretty! Nice pump!
My question with regard to a 30mm pump......is how did you keep it from bypassing the cooler. Or more accurately I should probably just ask what else is in the oil loop upstream of the pump.
Without mods I have almost always seen tight 30mm pumps on type 4 engines bypassing the cooler at highway rpm in anything less that 90° weather with 10/30 oil.
Orwell84...yes.....you can really tighten up a stock type 4 pump with careful lapping.....well all except for seriously worn gears.
Like this......?
https://www.thesamba.com/vw/forum/viewtopic.php?t=699156
Ray |
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Hoody Samba Member
Joined: November 28, 2007 Posts: 1948
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Posted: Tue May 15, 2018 8:59 am Post subject: Re: Melling High Volume Oil Pump for Type 4 Motor |
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Google typ4 olpumpe. A cnc aluminum 30mm one will pop up first. There are a couple places selling them. They also show up under the images. |
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WhirledTraveller Samba Member
Joined: January 09, 2008 Posts: 1399 Location: Cambridge, MA
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Posted: Tue May 15, 2018 2:23 pm Post subject: Re: Melling High Volume Oil Pump for Type 4 Motor |
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I didn't know they where still available. I recommend jumping on it if you need a pump, it's worth the money IMHO.
My engine is loose enough that I don't really have a problem. Oil cooler bypass is around 45psi. For me, at highway speed and around 180 degree oil 45 psi is what I see. Which is perfect. Any higher and I'd probably run hotter. _________________ 1977 Westy, Automatic. Big Valve heads, CS Cam. |
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orwell84 Samba Member
Joined: May 14, 2007 Posts: 2536 Location: Plattsburgh, New York
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Posted: Wed May 16, 2018 8:34 am Post subject: Re: Melling High Volume Oil Pump for Type 4 Motor |
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That's an excellent write up Ray. Thank you for that. My pump refresh was not nearly as comprehensive. We just used the best set of gears from the pumps I had and lapped the pump body and face to get the clearance down to something like .0015, which didn't require all that much lapping. We checked the clearances with plastigauge; quick and dirty, I know, but I think it will be a serviceable pump. I plan on building or having built a better pump with a more thorough going over.
I mostly want to test out whether the poor fit of the Shadek pump is the reason for my oil pressure issues and decide where to go from there. The next thing I have to figure out is a reliable way of removing the stock pump as I will have to check the clearance with the cam bolts. I have a Webcam with what appear to be unclearanced bolts, but to even check I need to be able to remove it again without beating the crap out of it. Somehow I haven't been able to manage this. |
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furgo Samba Member
Joined: September 06, 2016 Posts: 944 Location: Southern Germany
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Posted: Mon Jun 18, 2018 12:47 am Post subject: Re: Melling High Volume Oil Pump for Type 4 Motor |
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raygreenwood wrote: |
The RTV spot gasket |
I just came across this. Great writeup and excellent pictorial as usual. Thanks so much for posting it.
raygreenwood wrote: |
The basic Melling pump listed for type 4...for the life of me I cannot find the part # for....and there is not one listed in the parts finder on Melling's site.
It is actually slightly different than the type 1 pump...so slight that it really does not matter for interchangability...but at one time there was a part number for it. The outer plate was a little thinner and the inner boss was slightly lower.
It may be that it was actually one of the other versions....there are typically M79-A, M79-B and M79-C variants that range from four bolt to three bolt and dished to not dished cams and late type 1. |
Has there ever been a Melling oil pump that was specific for the Type 4, or was it perhaps a Type 1 one modified by resellers, as with other brands?
Short of them having missed to include it in their catalog, it's either that or that Type 4 pump was discontinued. Not even the Internet seems to show up any historical data on it.
Looking through Melling' Application search, or Parts lookup only returns the M-79C or M-79CHV for Type 1 engines:
https://www.melling.com/parts-lookup/
The M-79A, M-79B and their HV (high-volume?) counterparts also pop up if searched. But their description is exactly the same marketing blurb, which actually does not say anything about what they are or their gear size.
Update:
In fact, the only two places (at least from known vendors) where I've found a Melling Type 4 pump were:
Aircooled.net - US, NLA
https://vwparts.aircooled.net/MELLING-30mm-Cast-Iron-Oil-Pump-Type-4-Engines-p/melling-type-4.htm
Ahnendorp B.A.S. - Germany, seemingly still available
https://www.ahnendorp.com/VW-Type-4---Porsche-914-...anguage=en
The latter one shows the actual part number: M79AHV, which actually corresponds to a Type 1 pump. Whether the reseller modifies it to fit a Type 4, they don't say.
I later contacted Melling and the person I spoke to confirmed that they don't offer Type 4 oil pumps, and they didn't seem to be listed in their old catalogs either.
All in all, it might well be that all there is available today is the Melling Type 1 oil pump. _________________ '79 Westy, P22 interior, FI 2.0 l Federal, GE engine (hydraulic lifters)
Decode your M-Plate
Last edited by furgo on Mon Jun 18, 2018 7:16 am; edited 3 times in total |
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raygreenwood Samba Member
Joined: November 24, 2008 Posts: 21510 Location: Oklahoma City
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Posted: Mon Jun 18, 2018 5:09 am Post subject: Re: Melling High Volume Oil Pump for Type 4 Motor |
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furgo wrote: |
raygreenwood wrote: |
The RTV spot gasket |
I just came across this. Great writeup and excellent pictorial as usual. Thanks so much for posting it.
raygreenwood wrote: |
The basic Melling pump listed for type 4...for the life of me I cannot find the part # for....and there is not one listed in the parts finder on Melling's site.
It is actually slightly different than the type 1 pump...so slight that it really does not matter for interchangability...but at one time there was a part number for it. The outer plate was a little thinner and the inner boss was slightly lower.
It may be that it was actually one of the other versions....there are typically M79-A, M79-B and M79-C variants that range from four bolt to three bolt and dished to not dished cams and late type 1. |
Has there ever been a Melling oil pump that was specific for the Type 4, or was it perhaps a Type 1 one modified by resellers, as with other brands?
Short of them having missed to include it in their catalog, it's either that or that Type 4 pump was discontinued. Not even the Internet seems to show up any historical data on it.
Looking through Melling' Application search, or Parts lookup only returns the M-79C or M-79CHV for Type 1 engines:
https://www.melling.com/parts-lookup/
The M-79A, M-79B and their HV (high-volume?) counterparts also pop up if searched. But their description is exactly the same marketing blurb, which actually does not say anything about what they are.
All in all, it might well be that all there is available today is their Type 1 version. |
That is a tough question. At the time I bought the one I have.....which was maybe 1998 or 1999.....I bought it ....I believe.....from either V-Dub folks or Knights foreign parts in Dallas Texas.
They did not just work on ACVW....and when I went in and inquired....at least one was a Melling dealer.....and both had very low type 4 experience. When I asked.....they looked it up in their Melling catalog. So at one time.....they either had a part # or at least a notation in the book that one particular pump was correct for type 4.
The interesting thing is that it has plenty of room between idle shaft and cam bolts.....so fit wise....it does work quite well in a type 4.....except that outside the case....the lid will be hard up against the cooling shroud with maybe a 1/32" or 1/16" spacer to the shroud.
Here are some pics I posted in the other thread:
You can see the bilt clearance to a web #73 and hkw thick the outer flange is.
The one thing with these pumps....they fit the case just like stock pumps. Nice fit. Even though that fit will open up slightly because they expand at a different rate.....the volume this 30mm pump puts out is so high that loss would not be noticed. It can still bypass the cooler on a tight engine.
This pump and gears would be easy to machine down to 24mm.....taking 6mm out of the outer flange. If I could be sure that it would not make gears loose on the shaft.....it would be a good candidate.
I would bet that one of the three type 1 models...A, B or C.....has this shorter snout to work with a flat or dished cam gear. I will dig in my receipts and notebook and see if I have a part #. Ray |
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furgo Samba Member
Joined: September 06, 2016 Posts: 944 Location: Southern Germany
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Posted: Mon Jun 18, 2018 5:57 am Post subject: Re: Melling High Volume Oil Pump for Type 4 Motor |
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Thanks Ray.
I added a note about current vendors and after having contacted Melling on my last post, and I think we crossposted when you wrote your reply, so I'm not sure you saw the additional note.
Other than the fact that Melling don't seem to offer Type 4 oil pumps (at least currently), the other interesting bit was that the one vendor that advertises the Melling pump as Type 4 shows its part number as M79AHV, which is a Type 1 pump.
So from that and from what you are saying, it would seem that the only reason they are/were are advertised as Type 4 is/was because they have a spot on case fit and require no modifications to clear the camshaft gear bolts if present.
raygreenwood wrote: |
fit wise....it does work quite well in a type 4.....except that outside the case....the lid will be hard up against the cooling shroud with maybe a 1/32" or 1/16" spacer to the shroud. |
I've only done a visual inspection, without measurement. But as far as I can tell there is plenty of space between the stock pump lid and the fan shroud. Is the Melling pump's lid so much thicker that it sits against the shroud?
raygreenwood wrote: |
This pump and gears would be easy to machine down to 24mm.....taking 6mm out of the outer flange. If I could be sure that it would not make gears loose on the shaft.....it would be a good candidate. |
What about another approach? If the M79AHV is the "Type 4" one with 30 mm gears, perhaps the M79A with (supposedly) 26 mm gears is the one to get?
I'm not sure how much difference the two additional mm make (24 mm vs 26 mm), but the M79A might then be a good compromise between slightly higher flow than stock and not having to machine/modify the pump (except for the spot gasket, that is) _________________ '79 Westy, P22 interior, FI 2.0 l Federal, GE engine (hydraulic lifters)
Decode your M-Plate
Last edited by furgo on Mon Jun 18, 2018 7:17 am; edited 2 times in total |
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SGKent Samba Member
Joined: October 30, 2007 Posts: 41031 Location: Citrus Heights CA (Near Sacramento)
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Posted: Mon Jun 18, 2018 6:57 am Post subject: Re: Melling High Volume Oil Pump for Type 4 Motor |
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From my experience Melling does not make "stock" pumps. They have always been a racing / high performance pump line. As such, they always put out more oil pressure than stock pumps. Many racing motors that turn high rpms rely on slightly more clearance than stock engine because they flood the bearings with oil to keep it cool. Babbitt bearings melt if they get too hot. _________________ “Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin |
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orwell84 Samba Member
Joined: May 14, 2007 Posts: 2536 Location: Plattsburgh, New York
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Posted: Mon Jun 18, 2018 7:07 am Post subject: Re: Melling High Volume Oil Pump for Type 4 Motor |
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furgo wrote: |
Thanks Ray.
I added a note about current vendors and after having contacted Melling on my last post, and I think we crossposted when you wrote your reply, so I'm not sure you saw the additional note.
Other than the fact that Melling don't seem to offer Type 4 oil pumps (at least currently), the other interesting bit was that the one vendor that advertises the Melling pump as Type 4 shows its part number as M79AHCV, which is a Type 1 pump.
So from that and from what you are saying, it would seem that the only reason they are/were are advertised as Type 4 is/was because they have a spot on case fit and require no modifications to clear the camshaft gear bolts if present.
raygreenwood wrote: |
fit wise....it does work quite well in a type 4.....except that outside the case....the lid will be hard up against the cooling shroud with maybe a 1/32" or 1/16" spacer to the shroud. |
I've only done a visual inspection, without measurement. But as far as I can tell there is plenty of space between the stock pump lid and the fan shroud. Is the Melling pump's lid so much thicker that it sits against the shroud?
raygreenwood wrote: |
This pump and gears would be easy to machine down to 24mm.....taking 6mm out of the outer flange. If I could be sure that it would not make gears loose on the shaft.....it would be a good candidate. |
What about another approach? If the M79AHCV is the "Type 4" one with 30 mm gears, perhaps the M79A with (supposedly) 26 mm gears is the one to get?
I'm not sure how much difference the two additional mm make (24 mm vs 26 mm), but the M79A might then be a good compromise between slightly higher flow than stock and not having to machine/modify the pump (except for the spot gasket, that is) |
The M79A looks to have 21mm gears according to some vendor sites. The M79C seems to have 26mm gears. The Melling site does not seem to specify gear size... |
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furgo Samba Member
Joined: September 06, 2016 Posts: 944 Location: Southern Germany
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Posted: Mon Jun 18, 2018 7:29 am Post subject: Re: Melling High Volume Oil Pump for Type 4 Motor |
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orwell84 wrote: |
The M79A looks to have 21mm gears according to some vendor sites. The M79C seems to have 26mm gears. The Melling site does not seem to specify gear size... |
You're right. Although there seems to be some conflicting info between vendors on the gear size and whether the pumps are for flat or dished camshafts. A pity Melling don't list even the most basic technical info on their products, which adds to the confusion. _________________ '79 Westy, P22 interior, FI 2.0 l Federal, GE engine (hydraulic lifters)
Decode your M-Plate |
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