Blow by but dry compression above spec

[tkyanaga]

Hi all,

As the title states, I am having severe blow by, but my dry compression numbers are all above 276 PSI. Leaking valve cover gasket (by the brake booster) and there is visible gas coming from the oil fill cap if I open and set the cap on the fill hole.

I have been experiencing random shutoffs when driving it around the block for testing or moving for street sweeping. Does anybody know why this could be happening?
Secondly, what are my options to fix blow by? Change piston rings and hone cylinder or a tested long block -_- Anything else?


Other things to note:
oil pressure is at 40psi @ 2,000rpm when warmed up
I've swapped this into an MK1. It's not the prettiest, but it's in there.
It's in limp mode and I am going through this diagnostics list here


Here are my dry and wet numbers for each cylinder(#1 being closest to the belts):

1. 365, 425
2. 354.5, 425.5
3. 379.5, 413.5
4. 391.5, 440

I got an endoscope camera to shove in the hole from amazon (~$23) to check out the situation too.

(https://imgur.com/a/MVDX3mc)

EDIT (my diagnostic/final stretch of the conversion)
http://forums.tdiclub.com/showthread.php?p=5574302#post5574302

 

[AndyBees]

So, what engine are you working with? Miles on the engine?

Link to pics doesn't seem to work..

 

[KLXD]

Vacuum leak can cause apparent "blowby" since the pump discharges into the valve cover.

 

[WildChild80]

I was hoping that when I fixed my pump nipple it would reduce my blowby, I am running a 2.0 PCV vented to the atmosphere and my oil leaks have subsided but seems like I have lots on an ALH with 320k, and some extra sauce in the form of a tune making 23 PSI.

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[tkyanaga]

@AndyBees it was from a rear ended 2005 beetle, BEW 210,000 or 194,000 on the odometer. Just because it was hit, doesn't mean it was a great motor though.

@KLXD Will check the lines again, I just spent the $$ on a legit mityvac hand pump. Not going to mention what I was using before

@wildchild are you saying a good fix is to vent to atm? sounds like I'll end up with an oily engine bay

 

[mk4mr]

...needed to do a full flywheel/clutch job as well as engine and trans mounts...but since I don't have any of it yet, I was able to lube and even out E-brake cables and get them to actually even out and work properly.

 

[AndyBees]

Mk4mr, not sure what or you are replying to....

OP, all engines have blow-by! Keep that in mind! These diesel engines seem to have a little more than average. Not sure where you got the 276 PSI number as a base.

At 210k miles, I'd think the engine is fine unless the previous owner(s) abused it.

Considering this is a "conversion" project, the shut-downs could be anybody's guess.

I installed an E-vac Scavenger Kit on the ALH engine in my Vanagon to clear out the blow-by. It uses the exhaust to pull the blow-by out. Of course, the E-vac Scavenger connection to the exhaust must be beyond the muffler (will not work with exhaust back pressure).

If it starts good, I'd just keep driving it. This will allow you to iron-out the bugs as they pop-up.

Here is a link to an E-vac Scavenger .... https://www.ebay.com/itm/304-Stainl...295432?hash=item3d88648a48:g:vy8AAOSw8-lcxr3D

Here is a good YouTube demo by Summit Racing ... https://www.youtube.com/watch?v=Sw1EPnEoHJM

 

[WildChild80]

@AndyBees it was from a rear ended 2005 beetle, BEW 210,000 or 194,000 on the odometer. Just because it was hit, doesn't mean it was a great motor though.

@KLXD Will check the lines again, I just spent the $$ on a legit mityvac hand pump. Not going to mention what I was using before

@wildchild are you saying a good fix is to vent to atm? sounds like I'll end up with an oily engine bay

I have a tiny oil gauze filter and I've been watching for oil and haven't seen any yet. It's been 2 or 3 months and my engine bay is clean...now I do get some burnt diesel smell in the cab when I flog it and I suspect it's blow by coming from that vent, working on doing something slightly different in the future.

I did it for more than just leaking oil, positive crank case pressure hurts oil pressure and makes oil flow more difficult. I don't want to impede oil flow if I can help it.

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[mk4mr]

Mk4mr, not sure what or you are replying to....

OP, all engines have blow-by! Keep that in mind! These diesel engines seem to have a little more than average. Not sure where you got the 276 PSI number as a base.

At 210k miles, I'd think the engine is fine unless the previous owner(s) abused it.

Considering this is a "conversion" project, the shut-downs could be anybody's guess.

I installed a E-vac Scavenger Kit on the ALH engine to clear out the blow-by. It uses the exhaust to pull the blow-by out. Of course, the E-vac Scavenger connection to the exhaust must be beyond the muffler (will not work with exhaust back pressure).

If it starts good, I'd just keep driving it. This will allow out to iron-out the bugs as they pop-up.

Here is a link to an E-vac Scavenger .... https://www.ebay.com/itm/304-Stainl...295432?hash=item3d88648a48:g:vy8AAOSw8-lcxr3D

Here is a good YouTube demo by Summit Racing ... https://www.youtube.com/watch?v=Sw1EPnEoHJM

Oh gosh.....that was totally in the wrong thread. I have had to restart my PC 3 times now....sorry for the confusion....ugh....

 

[WildChild80]

I think the evac scavenger will be installed before the end of the semester, welding class will have some benefits soon, also thinking about welding an AN fitting in the valve cover for no more rubber bushing drama.

Andy, are you using a check valve where it meets the exhaust tube?

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[AndyBees]

To see my E-Vac Scavenger on the ALH engine in my Vanagon, click on the link below. Then, scroll down to the last post (#1328). There you will see a long list of links I prepared for the entire Thread relating to the various topics. Now, scroll down until you see the topic, E-Vac Scavenger Crankcase Gas Handling System (blow-by evacuation). There are three links showing the Post Numbers to what I did (pic heavy) ...

http://forums.tdiclub.com/showthread.php?t=276798&page=89

 

[Mongler98]

40 psi at 2k? Isn't that like really high? That's normal for not warmed up but for hot oil pressures should be half that. No?

 

[tkyanaga]

@AndyBees Thank you for mentioning the e-vac and that most engines have blow by. I thought I was going to be in the red for this project.
Got 276 PSI from the new beetle Bentley

https://imgur.com/2jEBX5L

@mk4mr Hope you found the right thread, LOL

@Mongler98 I read 29PSI @ 2k is the minimum and 103 PSI is the max.

https://imgur.com/zDssqZD

Went out partying, hope to get through a few diagnostic steps in the afternoon Sunday

 

[turbocharged798]

I don't believe that 276PSI number is right, under 375 PSI and you are going to have serious starting problems IMO.

Keep in mind that the Bentley manual is full of errors and misinfomation.

 

[Dh4276]

From VW shop manual

25-31 bar on new engine

19 bar is the min wear limit which equal 275 psi.

Max 5 bar spread from lowest to highest compression.

This is for the BEW like was listed out of the beetle above.

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[AndyBees]

40 psi at 2k? Isn't that like really high? That's normal for not warmed up but for hot oil pressures should be half that. No?

The ALH engine in Vanagon had 72 PSI with cold start-up when I first installed it in 2012 at 129k miles. Today, with 209k miles, on cold start-up the pressure is about 67-68 PSI.

Out on the road with the engine fully warmed up, oil pressure is about 45 PSI at or above 2000 RPMs. Considering that 4th gear in the Van is equivalent to 4th gear in an MK4 era Jetta, 70 MPH requires about 3000 RPMs which produces about 55 PSI oil pressure! Fully warmed-up, the oil pressure is about 28 PSI at idle.

 

[tkyanaga]

@KLXD I've got 26 in Hg going to the VAC port on my N75 valve. I don't think the pump is bad

The turbo actuator seems to be working at 3-17, maybe 18 in Hg. While driving around, I'm getting < 14 psi on the map sensor.

Since @AndyBees (thank you!) explained the blowby and ways to solve it, I'm going to start another thread for limp mode and shutoffs

 

[jasonTDI]

It's not blow by (mostly). It's a normal operation of this motor. And 276 compression. If you pulled all the glow plugs and test the car after a few revolutions the oil pressure is up and lubing. I've NEVER seen a cold motor 60F show numbers below 375. EVER. If your compression was actually that low the car would not start.

 

[tkyanaga]

Jason,

Can you elaborate on what it is, if not blow by? And what are you referring to, the engine leaking or the gasses coming from the oil fill cap?