High oil pressure and blow by

[maxyray]

Hi Guys,

I’ve got two oil related problems on my new motor. High oil pressure and its blowing oil out of the case at high rpms.

Here is a link to the build…
http://www.shoptalkforums.com/viewtopic ... 3&t=138344

Im running a duel oil relief case, 26mm pump full flow to a fram filter, cooler with 10w 40 oil.

I currently have:

Cold 50psi idle. (Cold day!)
hot 37psi @ idle -2000rpm or more 50-65psi.

From what I hear I should have:
hot 15psi @ idle - 35psi @ 5000rpm

The pressure is very steady and does not spike or more at all.

My first question is what should I do to lower my pressure? Is it bad to have oil pressure this high?

Secondly I have a lot of oil coming out of every possible place on the case. I’m running total seals and have a small bug pack breather that vents from both rocker covers and the oil filler tower.

Ive checked the breather and there is no oil in it.

How can I stop this???

Are the two problems related?

[Max Welton]

The term "blow-by" I have always associated with poor piston ring sealing. Combustion above the piston results in the passage of combustion gasses past the rings and into the case interior raising the pressure of the air inside the case. That in turn can cause air (and some oil) to exit the case around the pulley and up through the breather.

Note that nothing in the above has anything to do with oil pressure in the oil galleys.

Now if you mean something different by "blow-by" that could change things.

That said, your pressures seem to indicate oil that is too thick. Try 10w30.

Max

[maxyray]

The term "blow-by" I have always associated with poor piston ring sealing. Combustion above the piston results in the passage of combustion gasses past the rings and into the case interior raising the pressure of the air inside the case. That in turn can cause air (and some oil) to exit the case around the pulley and up through the breather.

Note that nothing in the above has anything to do with oil pressure in the oil galleys.

Now if you mean something different by "blow-by" that could change things.

That said, your pressures seem to indicate oil that is too thick. Try 10w30.

Max

Thanks for you’re reply.

Good to know that the two problems are not related.

I was running 20w 50 prior to the current 10w 40 and it didn’t make a noticeable difference!

I think I’ll start with some new oil relief springs and plungers just to make sure I’m running stock.

I was told by someone I can adjust and lower the pressure using this…
http://www.coolairvw.co.uk/Item/Shop...ief_Screw.html

But have read a few conflicting posts about it.

[Max Welton]

Cold 50psi idle. (Cold day!)
hot 37psi @ idle -2000rpm or more 50-65psi.

From what I hear I should have:
hot 15psi @ idle - 35psi @ 5000rpm

In order to evaluate these readings we must also know the oil temperature. I ASSumed that "hot" meant something over 200ºF. That would be a fully warmed up engine.

But this time of year, it is not uncommon to be over-cooling the engine (flaps and or thermostat missing). So ... is "hot" assumed or measured? Because the actual temperature makes all the difference.

PS: Just looked through your build thread. Nice work! But no thermostat. You need to get an some oil temp measurements.

Max

[jhoefer]

I was told by someone I can adjust and lower the pressure using this…
http://www.coolairvw.co.uk/Item/Shop_by ... Screw.html

But have read a few conflicting posts about it.

No. An adjustable oil pressure screw on the relief valve can only send more oil through the cooler for lower oil temps/higher pressures. It cannot increase temps / lower pressures below the stock value. Using it on the control valve will only allow you to increase the MAXIMUM oil pressure limit. The stock control valve opens at about 60 PSI. This item would allow you to change that to 70, 80, 90, etc PSI. You can never set it so the control valve opens below the stock value of 60 PSI. A likely result of using one of these is blowing your oil cooler from excessive pressure.

[Clonebug]

If you have blowby that showed up on your turbo engine you probably have the same thing that happened to Corysvdub and I.
He had blowby and ended up blowing his engine to kingdom come due to cracked pistons from detonation more than likely.

I also had blowby with excessive case pressure but after reading his problems I immediately took my buggy off the road and installed new barrels and pistons.
My blowby was gone with the new P/C's but I could not see obvious cracks in the pistons.
It was money well spent as far as I'm concerned.
If the piston breaks your complete engine and case will be toast.
Look up Cory's post...he had pictures of the engine and it was catastrophic.

[Steve Arndt]

What kind of pressure gauge? VDO???

I run 0W40 oil and a 26mm pump. Lots of pressure.

With regards to blow by, have you driven it enough to seat the rings?

[Ol'fogasaurus]

I have always been told that 60# when cold dropping down to maybe 40#s when hot, on a new engine, is about right. As the engine gets mileage on it the warm oil reading may drop. A gain of 10# per thousand RPMs on a VW is expected not to go over (roughly) 60#s of pressure. If the oil idiot light is fading in and out at idle that is usually around 7#s give or take. A good oil pressure gauge is a good thing to have as it will tell you if there is a problem long before the "idiot light" does but I still recommend having one.

High blow-by can be from several things such as rings not seated, the ends of the rings being in-line not off-set or piston problems but there are compression tests for the latter two.

Some types of rings have a rep to not seat especially in rebuilt engines where the cylinders were not honed or reusing pistons. If the heads were rebuilt and new seals added unless they were done wrong they shouldn't be a problem. I stretch the pushrod tubes a bit, put the good type of seals on and let the torquing of the heads on set the pushrod tube to size. As you torque things keep an eye on the tubes making sure that they remain in the proper relationship to the heads and case.

"... I’m running total seals and have a small bug pack breather that vents from both rocker covers and the oil filler tower.

Ive checked the breather and there is no oil in it." The red and italic part of what you said is the statement that has me going (I also have one of those blow-by kits).

Do the easy thing first, get rid of the hoses that come with the breather: they get pinched/kinked in the package and usually take a set and remain that way. Replace them with some good hose that came off a reel... not folded up. With no oil in the breather this seems to be the most likely problem.

I hope this helps but do the last anyway as: again, the empty breather is a bad thing if you are blowing oil out everywhere else. Also check the adapters into the valve covers to make sure that there is no blockage there. I once saw a pair of cast AL valve covers that had the bungs cast in but there was no hole clear through the bung.

Lee

[maxyray]

I totally forgot about this thread as i have been in the USA traveling for 6 months so haven't been able to do any work on the car.

I did a bit more research into the relief spring adjusters and found out they don't adjust the oil pressure just as Jhoefer said.

The plan now is to get an oil temp gauge to check the engine is getting up to temp and if it's not, I will get an oil thermostat cutoff to the rad and maybe some original fan housings flaps.

My oil pressure gauge is a Autometer Ultralite
https://vwspeedshop.com/product.php?pro ... 489&page=1

I was only thinking that I might be getting blow by because of all the little oil leaks I
Have (as I was very care to use a liquid sealant). After looking over my setup I did notice that my breather pipe from the filler is to small and needs to be 1/2".

Is there a way of testing whether or not I have blow by?

[Bruce2]

Is it bad to have oil pressure this high?

Yes.
High oil pressure is a measurement of what is happening to the oil after it leaves the pump. When you use thick oil, it cannot flow into the bearings as easy as thinner oil, so it causes higher back pressure.
Reduce your viscosity to 5W-30 and you will see better oil pressures (lower). More oil will be flowing into your bearings as a result. Isn't that a good thing?

Post a photo of your oil filler/breather.

[maxyray]

Is it bad to have oil pressure this high?

Yes.
High oil pressure is a measurement of what is happening to the oil after it leaves the pump. When you use thick oil, it cannot flow into the bearings as easy as thinner oil, so it causes higher back pressure.
Reduce your viscosity to 5W-30 and you will see better oil pressures (lower). More oil will be flowing into your bearings as a result. Isn't that a good thing?

Post a photo of your oil filler/breather.

Thanks I will try 5w 30 and see how I get on. What would you call normal oil pressure when cold and hot?

[Clonebug]

Here is a link you should read.

http://www.shoptalkforums.com/viewtopic ... 8#p1190228