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Discussion Starter · #1 ·
Help please guys

I'm racing for the first time in two days and I seem to have developed a oil pressure drop/ fluctuations when the temp heats up, I'm in the uk (that's pretty cold at the present) and I'm running 5w/40 syn oil at the moment. It's running a remote filter head and the bore temps go up to 120-130 deg when hot, that's tested with an infared temp gun on the bore fins. Help
 

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Is the pressure going up, and down, or does the pressure simply drop when the engine is warm? Heat thins oil, and it isn't uncommon to have a stock 1600 start out with a cold idle pressure around 50-60 psi, and drop to 15-25 psi when hot. What exactly are your pressures you're getting when you're having the issue? Do you have a deep sump on the engine, and if so, how did you extend the oil pickup tube?
 

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Discussion Starter · #4 ·
The oil pressure is around 60-70psi at 3000-4000rpm when cool, then when the temp rises it doesn't slowly drop, it comes down to 40-50 psi then start to Fluctuate and drop away to 20 and below some times, it has got a lower sump, but I didn't build the engine so I can't say about how it was done, I was wondering about a sticking relief valve but I'm not entirely sure where it situated, I think it might be vertically up on the left hand side of the engine as you look at the front pulley.
The engine has sprung a leak from what looks like the dizzy clamp bolt, which is near the pressure sender, but I can't see it cause this amount of pressure fluctuations, I'm going to sort the leak and retry today, baring in mind the uk is quite cold at the moment I didn't the 5w/40 was far off oil wise, I could bring it up to 15w/40 oil.
I could strip the engine down its just the time scale as I'm racing for the first time Friday.
 

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What pressure gauge? the electric ones are tempermental, mechanical gauge is much more reliable, also 20psi on idle hot is ok, what does it make at 4000rpm hot? does it use stock pressure relief valves in the case or a pressure relief oil filter head unit? the valve that controls overall pressure is at the flywheel end
 

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On my car I really am more concerned about the oil pressure at my shift point ( at least 10 psi for each 1000 rpm's ) . If your oil pressure isn't high enough at your shift point I would not race it until the problem is resolved to prevent internal damage. The pressure relief valve is located near the flywheel on the passenger side not near the pulley . A good investment is a VW shop manual . Good luck with your project, Mike McCarthy
 

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you need valvoline vr1 20w 50 oil to start with. and i'll say if its doing what you say then the oil pickup extension for the deep sump is not fitted correctly.
seen the issue before.
I've ran both street and race in the uk with no oil issues with vr1 20w50. high zinc content will make u huge difference to you engine life.
Race it if you fancy ****ing it up. seriously.
 

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How much oil do you run in your system ?
How did you record or measure the pressure fluctuation, meter only ?
If so, mechanical or electric ?
Do you know the pump gear size ?
Low style sump and large pump gear don't match is something
we learned the hard way. We lost 2 engines on #3 rod bearing failure
just by changing to low style/smaller sump. Previous engines ran
2-3 seasons on same bearings with larger sump and same pump.
We needed more sump to ground clearance, thus the change and
2 EXPLODED engines. My guess is we ran into oil foaming or
starvation problem due to lower oil volume.

I'm currently crewing a turbocharged alcohol drag bike team with
the latest data logging and you can see some serious oil pressure
variations even in a tried and tested combinations. Just a food for thought...

Pekka
 

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We run Lucas 0-20 synthetic race oil that has zddp already in it. Don't worry whether its good old dinosaur oil or synthetic as long as it has the zddp for your flat tappet cam. I installed an old school pressure boost kit ( stiffer spring) and I get app. 50 to 60 lbs with 30 wt. break in oil and app 30 to 40 lb. at idle using the 0-20 when warm. 70lbs at 3000+ RPM. I also use the wide thin line sump.
 

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it could be bearing clearances,it could be pressure relief piston is too small(bug pack had a batch that were .015 too small about a year or so ago),bearing clearances,loose iron pump and expanding case (plug case at pump outlet&pump out let when full flowed is done, I use welsh/push in plugs,not pipe plugs) or just some of all adding up.
 

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Discussion Starter · #14 ·
The engine only has a small 1.5 l second sump, I didn't build the engine so I'm not sure what the scavenger is like, the engine has already got a full flow system, and only had a problem on deceleration or after high rev's i.e. a burnout, I'm stripping the engine tommorrow to take a look.

Any other feed back would be appreciated.

Thanks Guys
Andrew
 

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Remember a lot of oil gets into the valve covers when it is revved up, it sounds like there should be enough with the small sump how deep does the extension go or is there one? How much oil is in the engine, is it worse once it gets hot? A friend of mine had an oil light coming on when revved up but the problem went away once a sump was added with the proper length pick up tube. If this is all ok you have bigger problems
 

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Discussion Starter · #16 ·
you need valvoline vr1 20w 50 oil to start with. and i'll say if its doing what you say then the oil pickup extension for the deep sump is not fitted correctly.
seen the issue before.
I've ran both street and race in the uk with no oil issues with vr1 20w50. high zinc content will make u huge difference to you engine life.
Race it if you fancy ****ing it up. seriously.

Hello bud when you say Vr1 20w50 I take it you mean valvoline?
 
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