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Fri Apr 21, 2017 11:51 am

OK, so since my 1915 is being rebuilt, I bolted a 1641 into my buggy. It runs good, sounds good and compression is between 115 and 130.
I took it for a ride to check things out and all was good for about 8 miles down a state highway. I then jumped on the interstate to get up to speed and by the time I got back to town (8 miles or so again) my oil pressure had significantly dropped off. 5 to 20 lbs.
So where do I start? oil pump??
Thanks guys.

Fri Apr 21, 2017 11:57 am

It sounds like you engine warmed up to me.

What was your idle and higher rpm oil pressure before and after the drive?

Otherwise it sounds normal.

Fri Apr 21, 2017 11:57 am

lots of people would be :lol: :lol: :o :D :shock: to have 20# hot idle oil pressure.

SO-need a bit more info- what are you used to out of that motor? Was it your first 80* day?

Anything different about that day as far as the motor was concerned?

EDIT-- so your hot idle at 700 is 5 :oops: as stated later- I would first go after the pressure relief plungers- then the pick up screen.

Fri Apr 21, 2017 12:28 pm

That was the first trip with that motor and I don't know much more about it as I bought it like that. The guy said it only had a couple thousand miles on it and he changed it out to put in a "snail motor".
It was only about 70* or so that day.

I just started it up now to give you some reference and, a cold engine at idle (900rpm) about 43# and at 2500 rpm, 58#.
The 5# pressure that day was when it was hot (about 190*) and idling. 20# was at around 2000-2500 rpm and also hot.
THis worry's the hell outta me as this is what my 1915 did and why I pulled it down. (It had part of a "wavy washer" go thru the cam gear and send crap thru all the bearings. As best we can tell.) God I hope this one isn't like that.

Fri Apr 21, 2017 1:15 pm

Run a heavier weight oil if you're worried.

Fri Apr 21, 2017 2:22 pm

I thought about that. I was thinking about a 20-40 or something (I only run Brad Penn) but, if there is a problem, I don't want it to be masked and just get worse. That is why I am asking what things I could/should check.
thanks for the idea!

Fri Apr 21, 2017 2:25 pm

What oil grade is in it now?
Next oil change it might be worth pulling the plungers in the case just to check they're free.

Fri Apr 21, 2017 2:28 pm

Normal oil pressure for a hot engine is 10 PSI per 1000 RPM. So 30 PSI at 3000 RPM should be considered normal. How sure are you that your gauge is accurate?

Fri Apr 21, 2017 5:45 pm

How sure of that oil pump are you? It might have the thick cover gasket on it. My GEX t-4 motor (just a heads up on doing stuff wrong) had a t-1 pump in it with gobs of sealer.- put a t4 pump on it and doubled the OP.-

SO- lots of stuff to look at that don't require a tear down-

Fri Apr 21, 2017 6:06 pm

I don't see a definite problem.
If the oil pressure DROPS below normal all of a sudden, THAT means something has occurred, but, what is "normal?"
IMO that IS normal for the average mostly-used up old VW engine, but what is abnormal is having a gauge :shock: It could blow up tomorrow or neat decade, you don't know.

The oil pressure being generally low isn't great, but boosting the oil pressure one way or another might do nothing or might cause problems.
Unless you have a reasonable idea of what's going on inside, the safer thing to do is nothing special.
Just keep an ear on, it and feed it oil the appropriate weight for how hot it's running.
Probably have to tear it down to see WHY it has low oil pressure.

yeah maybe it is the oil pump but if whoever built it can't get the oil pump right what's the chances they got anything right?
IMO run it or don't. Fix it right, or run it and see how long it goes. It's no fun to worry or take half measures.

Fri Apr 21, 2017 8:24 pm

My 1600 SP is lucky to get 20-25 lbs. oil pressure at 3200 rpm once it's halfway warmed up no matter what oil I use. Pressure is great when the motor is cold. So far I've put about 25,000 miles on it like that. No idea how many total miles it has. Drive it! 8)

Sat Apr 22, 2017 1:50 pm

Luke, it's 5-30.
When you say "plunger" do you mean the "caps" on top of the oil pressure springs?
I did not do much more than to start and run the engine a little, before I dropped the rear plug and installed a temp sensor. I hope that wasn't a bad idea, as I am told that is a good spot. I know it could go behind the crank pulley as well.

Dave, I haven't tested the accuracy of the gauge but they are (new) VDOs. I'm sure they could be bad from the factory but, I'd think not. They worked well on my other engine.

William, not sure at all. I have not taken it apart. It does have a cb oil filter hanging on it with a new Wix filter. I have another oil pump I could try....if i need to.

Modok, yeah, the engine could be worn out, as I really don't know if the guy lied to me or not but ,with the cylinder pressures being what they are, I think it's got plenty of life left. (I'm hoping).
I have read some people on here don't like to run gauges but, I prefer it. Especially since I am a bit new at this VW thing. A temp gauge helped me out with my last engine.
So should I jump up to 20-40 or 50, or even go to a straight weight? I understand some people like to run straight.
I'd rather do as you also said and see if there is something else wrong first. Not knowing if I got a "pig in a poke" is a little concerning, at least till I have some miles on it.
You are correct about not worrying, that is why I run gauges. I don't worry then.
(It reminds me of a guy asking another guy about him carrying a gun: he asked if he was paranoid and the other guy said not when I carry. :))
I intend to run it but, since I'm not sure what I have, a wanted to maybe get a little insight on what I might check to make sure - if there actually is something to check. If not, we'll cross our fingers and "damn the torpedoes"! :)

Thanks SBD.

Sat Apr 22, 2017 2:23 pm

Example: if you have low oil pressure because of some problem with the case(lifter bores, spread case, plungers worn out)......but the rod bearings are tight........you run 20-50 and you might burn up a rod bearing.

Oil get thinner as it gets hot.
If the thing likes to run hot, over boiling oil temp all the time, in a bus and lets get on the highway, I'd go for 15-40 or 20-50, as once it's up to temp that will work.

But a buggy........it's probably not going to be very hot most of the time, and very tempting to get on it before it's warmed up, so running heavy oil might be risky unless it is built with generous clearances on everything, and it probably isn't.