XR engine problems

Its been a tough year for the car. I really have not had the propert time to get it healthy. We swaped a newer head at the end of last year to solve some leaking problems. After swapping the head we immediately starting having lots of oil in the intercooler.

After isolating the breather and PCV. Oil comes out the valve cover breather under load. Not sure what the cause is. Looking for advice.


Leakdown test results (air was traced to leaking out the oil filler):

1 - 25% 2 - 25% 3 - 25 % 4 - 31%

Dry Compression:

1 - 145 psi 2 - 150 psi 3 - 145 psi 4 - 150 psi

Wet Compression:

1- 150 psi 2 - 152 psi 3 - 150 psi 4 - 151 psi

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Matt Smith

Racing in glorious black and red

My daily life is a Saab story (sold!)

Somethings stuck. I had this happen a couple of years ago on the street car. It actually blew out a rubber valve cover gasket. It's the crank case pressurizing. Do you have a check valve on the PCV or is it running to atmosphere? If running to atmosphere(and not the intake) remove the PCV. If running to the intake get a check valve from the vacuum line that runs to the brake booster from most any 70's or 80's Nissan, you'll know it when you find it as there are SS. Make sure to orient it so that it's blocking boost to the crank case. And every so often you'll need to clean it. I would just run the hose to atmosphere. Also you might want to put some sort of filter on the end of the hose to keep dirt out. Compression looks good. And all the cyclinders are within 15%. Are you still using the stock Ford electronics?

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Scott Manley
Spokane, WA
86' XR4Ti
37

In trying to narrow down the problem. We vented the PVC to atmosphere and the valve cover breather to atmosphere. No harm in taking the PCV off entirely.

If its not blowby of the rings. I am suspicious of a clogged or poorly functioning valve cover breather.

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Matt Smith

Racing in glorious black and red

My daily life is a Saab story (sold!)

Hi Matt,

BTW, there will ALWAYS be some crankcase pressure, and more at heavy engine loading is normal. Hence the reason for PCV systems on newer cars and breather tubes or air/oil separators on older engines. If you vent the crankcase to atmosphere, you will always see some oil/oil vapor coming out. The question is; did this increase with the head change? Sounds like it did. Also, how does it get into the intercooler? Does the breather vent to a point in the air inlet in front of the intercooler?

First, I assume the 'wet compression' is with a bit of oil in each cylinder? Note that this technique only helps you troubleshoot if any cylinder leak is due more to valves or rings, and doesn't really tell you much useful about overall compression. The dry readings are more important.

Do we assume that this oil-in-the-intercooler was not happening before, and started after the head change? If so, do you think that there is any chance of a head gasket not being well sealed and allowing a bit of combustion pressure to leak into an oil passage? It would not take much to cause a very noticable amount of pressure in the crankcase, and could easily be such as to show little or no decrease in cylinder testing compressions, particularly hot vs cold. (This happens with head cracks that allow a bit of compression gases into the water jacket but can cause significant overheating; very little change is seen in compression testing, if at all.) The slighty higher leakdown of #4 is an area to look at, as one would expect an oil drain passage back there. Did you use head studs, and was the newer head checked closely for warpage prior to installation? If not, I would think seriously about this area, and consider pulling the head and having it milled flat.

BTW this is just general adivce and observations; I don't know the quirks of your engine. Someone else may know some quirky problem right off, so I would make more queires before acting on my input alone.

Also, we ran the prior Starion engine with a lot of blow-by that ended up with some oil in the turbo compressor side and in the intercooler for quite a while with no problems. (I set the piston clearances too large for the type of pistons being used, hence the excess blowby.)

Regards,
Mark B.

Yep, all the problems started with a head change (Note: the head came from an engine with a reported pressurization problem)

Your comments on the compression test and source of the oil is correct. We use head bolts.

Your diagnosis sounds reasonable and I was already planning to pull the head and check the gasket and surface this weekend. May also retorque the head.

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Matt Smith

Racing in glorious black and red

My daily life is a Saab story (sold!)

Here's a link to the oil schematic-
http://www.turboford.net/ubb/uploads/00009141/Engine%20Lubrication%20small.JPG

I know my old house mate once set a head on the new gasket without torquing down the bolts and left it overnight. He completed the job the next morning. HG didn't last a day and it blew oil out the intake side of the gasket.

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Scott Manley
Spokane, WA
86' XR4Ti
37

This one has got me stuck. I have been torn between the need to know exactly what the problem is and the simple solution of swapping the engine with another one that is sitting in the shed. Should be an interesting weekend.

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Matt Smith

Racing in glorious black and red

My daily life is a Saab story (sold!)

mothra Wrote:
-------------------------------------------------------
> This one has got me stuck. I have been torn
> between the need to know exactly what the problem
> is and the simple solution of swapping the engine
> with another one that is sitting in the shed.
> Should be an interesting weekend.
>
> Matt Smith

Matt, get a gasket set, and tear down the spare engine.
Get the 3 quart can of Gunk Carb and choke cleaner and soak each piston in the stuff for 12 hours and clean with some used Scotch brite and use the rings to squeegee out the carbon in the grooves.
You gotta get the grooves spotless then measure the side clearance with NEW rings.

It's smarter to do this once than install motors three times.

Cylinder wall clearance is important, and finish is too but ring groove side clearance is critical.

This tear down will give you a chance to see how the rod upper shells and main bearings look, if the look good, they ARE good.
(Wash your hands once you have the thing opened up.)

It'll also give you a chance to spiff things up and paint the engine....
should I suggest a color?????

And you could do ther chassi rail mounts, the sleeker, smoother, cheaper MkII versions. I have the sheet metal done.....

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John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

Well, in short we still ddo not know specifaclly what the problem was but we switched out the head and the problem is solved. I suspect that the head is cracked or a bad valve seat or similar.

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Matt Smith

Racing in glorious black and red

My daily life is a Saab story (sold!)

How was the head gasket? Do you have a picture?

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Scott Manley
Spokane, WA
86' XR4Ti
37

No picture but the head gasket was fine.

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Matt Smith

Racing in glorious black and red

My daily life is a Saab story (sold!)