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Roxy Rose
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Joined: October 28, 2015
Posts: 4
Location: so Cal
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 Posted: Fri Nov 13, 2015 9:22 pm Post subject: Porsche 914 running too hot Help !! |
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okay, here is the low-down.
I have a 1974 914. 2.0. It had been sitting for many years until I got it. It had several issues but I managed to get it up and running. It has the original fuel injection.
Compression (ok) 125 lb on all four.
Timing Checked and rechecked and holds steady.
Mixture good. On the rich side if anything.
Valves adjusted and again for a second time just to make sure.
Oil (20/50) changed initially and again after 200 miles.
No obstructions in the fan area that I can see.
Oil cooler looks clear with no caked on grease and dirt.
Changed oil temp sensor and gauge.
Oil pressure 50/60 on hiway and 20 at idle.
Checked oil presure relief valve. Looked good with no scaring.
All tin is in place. No fins on heads broke that I can see.
It likes to run down the hiway on a cool day at 210* up a hill or in traffic it heads up to 240. At that point I have to pull over and let it cool down.
It does have a miss every now and then but nothing too annoying. I did notice that one fin on the fan is missing but otherwise it looks good.
What am I overlooking ???
Is there anyway to verify if the air is cucirlating as it should?
Can one fin missing on the fan cause such overheating?
Could the fan be the wrong one? For a 1.8 instead of a 2.0
Can the fan be replaced without dropping the motor?
Besides having a 914 when I was young but never really working of one. I am not that familiar with these cars. Any help would be greatly appreciated.
Roxy |
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Wolfgangdieter
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Joined: June 25, 2008
Posts: 1958
Location: FL Panhandle
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| Posted: Sat Nov 14, 2015 7:38 am Post subject: Re: Porsche 914 running too hot Help !! |
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Did you have all the tin off the block? Mice like to make nests and stash food over the piston cylinders. Try looking down where spark plugs go thru the tin. A pressure washer might blast it and grease out. I get a good complete fan - I don't think there is a difference between the 2 fans. Are you using stock heat exchanges with all the tubing and valves set up on it.
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CMC '57 Porsche Speedster Replica and Dolphin boat tailed full pan VW MOD-T Street Buggy |
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thesatanicmechanic
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Joined: November 30, 2008
Posts: 102
Location: Charlotte, NC
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| Posted: Sat Nov 14, 2015 9:36 am Post subject: Re: Porsche 914 running too hot Help !! |
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What is the timing set to? 28-30 degrees total advance (3500 rpm) with both vacuum hoses disconnected & plugged?
Is the thermostat installed? Is it stretched when cold? are the thermostatic flaps working?
Like Wolfgang mentioned too: Inspect for rodents?
The cooling fan should be replaced, a broken fin will throw it out of balance. Drop the engine to replace it, remove all the sheetmetal while you're at it and inspect for obstructed cooling. |
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raygreenwood
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Joined: November 24, 2008
Posts: 21512
Location: Oklahoma City
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| Posted: Sat Nov 14, 2015 10:22 am Post subject: Re: Porsche 914 running too hot Help !! |
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Also get rid of the 20/50 oil. Its unnecessary in any of the stock type 4 engines.
10-40 or even 10-30 are just fine.
The issues are:
A. The heavier the oil the harder the oil pump and engine have to work....more power loss and more friction. This is relatively minor...but adds to the whole.
B. Its a common problem that the heavier oil...especially when its starting to get cooler outside....and it stays thicker longer.....creates excessively high oil pressure. This pressure keeps the piston in the oil relief valve pushed down....oil vents to the case instead of going through the oil cooler....meaning no oil cooling.
All of the fans for type 4 engines...1.7, 1.8, 2.0...are all the same...except for the timing marks on some.
Also inspect your plugs...make sure you are not running lean. Check your advance with a timing light....hoses off first...revving up to 3500. Then with hoses on so you can see total advance.
If for any reason your ignition is either under advancing or over advancing ...both issues will cause hot running. Ray
EDIT: Your oil pressure....with the 20/50...is a bit telltale. Its nice to have 20 psi at idle (exactly 20 psi...or does the needle blip up to say...21-22 as it idles?).
A solid 20 psi is a little rare to have when warmed up at idle....if your gauge is accurate......typically between 10 psi at lowest to 15 psi solid at idle is normal. The idiot light comes on between 6 and 8psi IIRC.
And....having 50-60 psi at highway speed is also relatively normal....but at what rpm? Its generally held that 10 psi per 1000 rpm + 10 psi extra is normal ......so at 3500 rpm...about 45 psi is normal. having 50 psi is not an issue....but having a solid 60 psi at highway speed say...in the 3000-3500 rpm range....is telling.
What you need to do is to get a MECHANICAL oil pressure gauge and plumb it into the oil pressure light switch location. Use a brake hose...check the thread mating carefully....make sure its the proper thread and taper...and dont tighten it hard. The hose will cost about $15. You can use a 60 psi water pressure gauge from Home Depot if you want.......but you want to see exactly what the real oil pressure is.
Many oil pressure gauges are notoriously off. The issue with 20/50 oil bypassing the oil cooler is a common one.
20/50 oil is only needed in the very hottest weather....think west Texas and Death valley. Ray |
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VWCOOL
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Joined: June 02, 2006
Posts: 1821
Location: Down under
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| Posted: Sat Nov 14, 2015 4:49 pm Post subject: Re: Porsche 914 running too hot Help !! |
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Your engine is more than likely behaving exactly the same as it did in the 2000s, the 1990s, the 1980s and the 1970s. It's great that you are trying to look after your engine, but an hour spent 'researching' mythinformation and unsubstantiated opinions on the interwebs has you unnecessarily worried.
You have checked all the basics - good work. You might also check the temp sender/sensor and gauge for accuracy - it may be inaccurate or imprecise
240F is NOT "too hot" or "overheating" for an aircooled engine. Although most engines, most of the time, will run cooler than this, this temp is in the range of normal and is NOT, in itself, indicative of a problem, as you think
NEVER 'cool an engine down' by pulling over!!
Last edited by VWCOOL on Tue Dec 08, 2015 4:11 am; edited 1 time in total |
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raygreenwood
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Joined: November 24, 2008
Posts: 21512
Location: Oklahoma City
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| Posted: Sat Nov 14, 2015 8:26 pm Post subject: Re: Porsche 914 running too hot Help !! |
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| VWCOOL wrote: |
Your engine is more than likely behaving exactly the same as it did in the 2000s, the 1990s, the 1980s and the 1970s. It's great hat you are trying to look after your engine, but an hour spent 'researching' mythinformation and unsubstantiated opinions on the interwebs has you unnecessarily worried.
You have checked all the basics - good work. You might also check the temp sender/sensor and gauge for accuracy - it may be inaccurate or imprecise
240F is NOT "too hot" or "overheating" for an aircooled engine. Although most engines, most of the time, will run cooler than this, this temp is in the range of normal and is NOT, in itself, indicative of a problem, as you think
NEVER 'cool an engine down' by pulling over!! |
No....its not really excessively hot.....but 240 is just about at the running limit. Its a little on the high side of steady running temp for a stock engine.
And...again...dump the 20/50....its known to cause oil cooler bypass in engines that in normal tolerance. Its unnecessary. Ray |
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VWCOOL
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Joined: June 02, 2006
Posts: 1821
Location: Down under
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| Posted: Sun Nov 15, 2015 3:47 am Post subject: Re: Porsche 914 running too hot Help !! |
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Are you sure that is "known", Ray, or is it interwebs typical cut 'n paste myth-information?
240.. what do you mean by 'running limit'.. is that a VW specification, an oil company spec, or just where many/most air- cooled motors seem to operate, most of the time?
How does the viscosity of different oils - for example, 10-30 and 20/50 - differ at, say, a typical VW running temp of 100 to 110C? |
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raygreenwood
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Joined: November 24, 2008
Posts: 21512
Location: Oklahoma City
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| Posted: Sun Nov 15, 2015 7:43 am Post subject: Re: Porsche 914 running too hot Help !! |
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| VWCOOL wrote: |
Are you sure that is "known", Ray, or is it interwebs typical cut 'n paste myth-information?
240.. what do you mean by 'running limit'.. is that a VW specification, an oil company spec, or just where many/most air- cooled motors seem to operate, most of the time?
How does the viscosity of different oils - for example, 10-30 and 20/50 - differ at, say, a typical VW running temp of 100 to 110C? |
EDIT: Because the long reply....I am adding this edit in at the front to help answer one of your other questions. In general...oil temps need to reach 220F to evaporate water vapor that is entrained in the oil. Typical safe oil temp levels for.... sustained running....for conventional dino oil are about 265-275F. From there it starts breaking down. Synthetics can run to 300-325F sustained....but about 350F starts causing the same problems.
The reason I mention "sustained"...is that its not the common running temp that causes the problem. Its the PEAK oil temps....which happen on short bursts of acceleration like getting on the interstate or climbing a hill...where oil can pick up an easy 30-50F in the blink of an eye. These peaks are what the oil cooler is really needed for.
Its these high temperature peaks....several a day...many per month....and their cumulative time...that really take the toll on oil. It literally "breaks" ability of the oil to sustain film strength and degrades the lubricant additives and their anti-scuffing abilities.
And.....since oil is a relatively dense liquid (even with its relative low viscosity)....it does not shed heat with extreme quickness. The standard oil cooler trip/coursing....will only drop temps on the oil going through it...about 10-15F. A larger/longer cooler can drop the oil 25-30F or more with each pass through. If your oil is running in the right temp range in the first place...a 10-15F drop is all that is required.
This is why you need to make sure that your standard running temp is not so high or close to the high end of normal that the peaks of temp bump it up into the danger zone for longer sustained times. This is a short but well written snippet of the zillions of pages online about oil temps.
http://www.hotrod.com/how-to/engine/1310-engine-oil-temperature/
Also....its not about what is right for an aircooled versus water cooled or any other engine. The oil has no idea what kind of engine its in or what brand of crankshaft its running against.
Its about film strength and temperature range to protect that film strength....and its about shearpoint/shear-thinning (which drops as the temperature rises with oil....but not all liquids) and recovery time ....which is key....which means after the oil pump has sheared the oil dropping viscosity say....by more than half....which is common.....how fast does the oil regain its viscosity and film strength as it comes out of shear into the crankcase where is not under pressure any longer and as temperature drops.
Motor oil is relatively slow in viscosity/film strength recovery after shear and heating compared to other liquids. This is both a strength and weakness.
As for the 20/50 oil and pressure relief issue:
I learned it the hard way before there was an internet.
Sadly on the first two engines I damaged for sure....I passed off the oil overheating issue as fuel tuning and hot climate driving.
The REDUCED oil flow with 50 weight oil....which is what this really causes. ......because there is always some amount of oil flowing through the oil cooler even when cold because the relief piston does not seal on the port.........is low pressure and low volume oil through the oil cooler when you use 20/50 at high rpm. The oil cooler....which is a good design but rather small.....has only a fraction of the cooling ability when the oil is under very low pressure.
I figured this out when I installed a larger external cooler with an electric fan. The stock cooler inlet/outlet ports were blocked and an elbow added at the end of the original factory drilling.
The engine ran just as hot at highway speeds. Imagine my surpise when the cooler developed a crack while I was working on it (it was used.....I was in college....money was in short supply).....and when warmed up.....the volume of oil passing through the cooler when the engine revved past about 2000 rpm..... dropped to a trickle. Drop rpm to between 1200 and 2000.....and the oil volume and pressure increased 2-3-fold...spraying everywhere from the crack.
At the time....I passed it off as an oil feed problem at the cooler inlet. As I was working with the problem I switched back to cheaper oil....the Valvoline racing 20/50 was expensive in those days.
I removed the external cooler loop and put in a bypass hose between inlet and outlet ports with pressure gauge.
I went to sae 10/30 and the pressure remained high across the rpm range.
In those days I still did not make the relief valve connection. I just did not know enough. I just assumed that the oil was too heavy for the engine in some way.
The interesting part is that ......sometimes .....the 20/50 flowed almost normally through the cooler loop. Those times....were when the oil was literally so hot it was smoking.
I didnt make the real connection until about 10 years ago when others including Jake Raby were working on this on the STF....and I dug out my notedbooks.
From that motor forward....I had been using Sae 30 in winter and summer with normal oil 5emps all stock and no issues.
As for viscosity changes......50 weight is normally just over 20% higher viscosity. .....but the the viscosity is NOT the most critical difference. The film strength is much higher and that makes the SHEAR STRENGTH or shearability of the oil a couple orders of magnitude higher for 50 weight as compared to 30. This means that the 50 weight does not shear thin or heat thkn as readily and has higher tack rate or "cling-ability" to parts...and those parts include the walls of oil passages. In effect....in a system not designed for its use.....the oil can become its own restriction.
And....I know this to be fact. I work with viscometry for a living. I have had motor oils....cold and hot on both the rotational viscometer and the rheometer in several of plants I worked in.
This is not a problem......if there is not an engineered weak point to relieve that pressure (the relief valve spring). Yes....the relief valve spring can be made stiffer to not vent as easily......but this will cause other problems.
For one...in cold weather.....pressure will be enormously high. I exploded one oil filter and bulged another at about 30F with 50 weight oil. I passed it off as crappy filter.....yes it was a fram. The wix filters did not expand......but this also pumped my oil pressure in the mid rpm ranges to excessive numbers at the cooler loop.....about 80 psi without messing with the relief valve.
If you put a stiffer spring in.....it will be higher at idle and mid range. Too high for the cooler.
The other issue is that in traffic where rpm stays in the low to mid range in hot weather.....the stiffer piston spring will reduce the oil flow through the cooler.
Yes....you can use 20/50 or sae 50 in a type 4 for high rpm work.....but also use an external cooler and filter system with its own larger bypass valve along with the piston spring and piston mod.
I bring the point up whenever I see it as a problem in what someone is working on. I generally stay out of the arguments because they turn to BS very quickly....and I know only enough about the viscosity and shear of motor oils to understand how they work and what they can cause when they are energized. I dont have the time to get into testing and study to prove my point in the forums whenever the oil weight and relief pressure piston comes up .....as it always does.
I know it to be a problem for stock engines.....most especially engines that are in good shape with tight bearings.....and that is KEY. You will hear no end when this comes up of people who state "I have been running 50 weight oil for eons with no problems".......and when you start looking at it.....how many of these owners even have an ACCURATE temp gauge?.....how many run in hot weather and would even notice high oil temps?......how many have worn engines and original high mileage oil pumps....which bleed lots of pressure off?.....and how many have the idea that oil temps above 240 sustained....are normal?
Yes...oil can handle peaks of temp up to about 300F. But sustained running should be above 185F to be called warmed up.....and 190 to about 220 sustained. Above that is too hot for long stints. Ray |
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VWCOOL
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Joined: June 02, 2006
Posts: 1821
Location: Down under
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| Posted: Sun Nov 15, 2015 8:53 pm Post subject: Re: Porsche 914 running too hot Help !! |
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| My dishes dry just fine without it being a 220F day outside... |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21512
Location: Oklahoma City
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| Posted: Sun Nov 15, 2015 10:40 pm Post subject: Re: Porsche 914 running too hot Help !! |
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| VWCOOL wrote: |
| My dishes dry just fine without it being a 220F day outside... |
You wash your dishes with motor oil emulsified with water?  Thats just plain water...all by its lonesome. That does not exist once the moisture has been sheared into the oil. And....as it combines with oil into an emulsion....the boiling point rises slightly...and is also affected by atmospheric pressure.
This water primarily comes from piston blowby. It takes about 220F to evaporate that out. In the winter or in a cool running engine......you can get away with sustained running oil temps of 185-200F....simply because you WILL have short temperature peaks 25-50F higher when you accelerate heavily or load the engine on a hill.
The problems come when you have the "little old lady syndrome"....wherein the car is driven for short hops and never allowed to fully warm up or hit temp peaks. You get that "mayonaise" sludge in the oil breather and valve covers. Emulsified oil and water. It will trash an engine. Ray |
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Roxy Rose
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Joined: October 28, 2015
Posts: 4
Location: so Cal
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| Posted: Tue Nov 24, 2015 5:00 pm Post subject: Re: Porsche 914 running too hot Help !! |
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Okay, I changed the oil to a lighter grade and no change. so I pulled the old fan off and replaced it with a good one. Made sure the timing marks were right on. But still no change.
Now I have heard people talk about driving habits and I assure you this has not helped at all. In fact if I drive trying to keep the rpms above 3500 it heats up even more. Also someone had said that I should not shut it off to let it cool down but instead stop the car and keep the rpms up around 2000 to cool it down but if I do this the heat continues to rise.
I guess my next step will be to pull the fan should forward and see if I can remove the oil cooler to check for any blockage.
Being that the heat continues to rise at a fast idle once it has heated up does this sound like an air circulation problem or a problem with the oil circulation?
Any other |
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Jacks
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Joined: July 15, 2006
Posts: 2347
Location: San Clemente, Ca.
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| Posted: Tue Nov 24, 2015 6:01 pm Post subject: Re: Porsche 914 running too hot Help !! |
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Sounds like the themostat flaps/return spring, are missing/installed wrong. Even with a defective bellows or cable, the system default is made to set the flaps to full hot, even when cold. Warm up will be slow if so. The arrangement of the installed flaps is a bit counter intuitive, as the flap over the oil cooler must be fully closed on hot running. There is a spring on the horizontal linkage rod that must be in place to hold the flaps in the correct orientation. Furthermore, there is a short horizontal linkage on the large flap that directs air to the oil cooler. I have seen a few examples where this short linkage has been inverted, with the flaps forced in to the shrouding in the wrong position, resulting in high oil temps. Remember, the oil cooler flap must be installed in the fully closed position over the top of the oil cooler when fitting the fan shroud on the engine to direct air to it! If the spring is missing, broken, or off of it's perch, the flap will not be in the correct position.
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Roxy Rose
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Joined: October 28, 2015
Posts: 4
Location: so Cal
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| Posted: Tue Nov 24, 2015 6:56 pm Post subject: Re: Porsche 914 running too hot Help !! |
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I have to admit I am a bit confused as to how the flaps work because I can not see them. I don't think the bellows is working as there is no tension on the cable weather cold or hot. The spring is in place and working. The way I tested it was to have the engine running then pull a plug wire out and feel for air blowing by. There is a light stream of air circulating. If I manually push the flapper rod in the other direction the stream of air stops blow through the plug wire hole. Make sense??? So I think it may be working though I can't say that there is an awful lot of air blowing by. But this is at idle and I also have nothing to compare it to.
I really appreciate all the help here. I have nothing against going to a mechanic but I feel very determined to do this myself. Well with the help of you guys.
When I got this car it had a 1.8 carbureted motor on its last leg. It had burned valves and back fired badly. The idle was all over the place but the dang thing ran cool. Around 180-190 most all the time. I know there is something that must be wrong here.
Yesterday coming home from bakersfield on mostly flat ground on a cool day the car gradually got up to 230. Then when I stated climbing the hill it got to 240 and I pulled over. I tried to let the motor cool down running at a high idle but the temp just kept climbing so I shut it off.
Thanks in advance for all your help, Roxy |
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raygreenwood
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Joined: November 24, 2008
Posts: 21512
Location: Oklahoma City
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| Posted: Thu Nov 26, 2015 2:57 pm Post subject: Re: Porsche 914 running too hot Help !! |
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| Jacks wrote: |
| Sounds like the themostat flaps/return spring, are missing/installed wrong. Even with a defective bellows or cable, the system default is made to set the flaps to full hot, even when cold. Warm up will be slow if so. The arrangement of the installed flaps is a bit counter intuitive, as the flap over the oil cooler must be fully closed on hot running. There is a spring on the horizontal linkage rod that must be in place to hold the flaps in the correct orientation. Furthermore, there is a short horizontal linkage on the large flap that directs air to the oil cooler. I have seen a few examples where this short linkage has been inverted, with the flaps forced in to the shrouding in the wrong position, resulting in high oil temps. Remember, the oil cooler flap must be installed in the fully closed position over the top of the oil cooler when fitting the fan shroud on the engine to direct air to it! If the spring is missing, broken, or off of it's perch, the flap will not be in the correct position. |
Yes. and no. If the spring is broken or missing...it can mean the flaps move around. If the thermostat fails...the flaps pop all the way open.
You are dead on right that if the little linkage on the oil cooler flap is inverted...it can make the flap flip the wrong way. BUT....though this an slow warm up...it will not starve the oil cooler of air. it loses 10-15% cooling efficiency but still gets most of it.
If you disassemble the cooling shroud you will see the cast in scoop that allows the oil cooler to get a large amount of forced air no matter where the flap really is. Yes...its best when the flap is down all the way....but this is most likely not the problem. Ray |
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raygreenwood
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Joined: November 24, 2008
Posts: 21512
Location: Oklahoma City
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| Posted: Thu Nov 26, 2015 3:10 pm Post subject: Re: Porsche 914 running too hot Help !! |
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| Roxy Rose wrote: |
I have to admit I am a bit confused as to how the flaps work because I can not see them. I don't think the bellows is working as there is no tension on the cable weather cold or hot. The spring is in place and working. The way I tested it was to have the engine running then pull a plug wire out and feel for air blowing by. There is a light stream of air circulating. If I manually push the flapper rod in the other direction the stream of air stops blow through the plug wire hole. Make sense??? So I think it may be working though I can't say that there is an awful lot of air blowing by. But this is at idle and I also have nothing to compare it to.
I really appreciate all the help here. I have nothing against going to a mechanic but I feel very determined to do this myself. Well with the help of you guys.
When I got this car it had a 1.8 carbureted motor on its last leg. It had burned valves and back fired badly. The idle was all over the place but the dang thing ran cool. Around 180-190 most all the time. I know there is something that must be wrong here.
Yesterday coming home from bakersfield on mostly flat ground on a cool day the car gradually got up to 230. Then when I stated climbing the hill it got to 240 and I pulled over. I tried to let the motor cool down running at a high idle but the temp just kept climbing so I shut it off.
Thanks in advance for all your help, Roxy |
As others have noted....230-240F is the normal limit of fully warmed up. You are NOT overheating. Just because your engine previously ran 180-190...does not mean that THAT was correct. 180-190 is the LOWER limit. Its not bad...but its rather cool. It MUST spike higher here and there on acceleration.
If it does not climb over 240 with constant state driving....meaning just cruising flat level and constant at highway speed.....then you have no problems.... (it will spike higher when climbing a hill or hard acceleration but should drop within a minute or two of stable driving again).
If in fact it was rising over 240F...through 250 (still not insane) and up to 265F...and does not begin to cool down in 2-3 minutes of steady state driving ...then YES...you are running too hot.
And....this is the exact symptom that running 20/50 oil CAN cause. Its totally unneeded for this engine and DOES cause issues with oil pressure bypass. If you feel you need a heavy multigrade...10-40 and 15-40 work well.
But..check and fix your flaps and bellows first. If the thermostat bellows is not working...10-15% of oil cooling you are losing could just be the difference. Ray |
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