Engine/Transmission (1994 - 1998) Blow-by?

[JBeasley]

A friend of mine has a 98 12 valve that was leaking oil around the injector nuts, alot of it. We pulled the injectors and they were dripping wet with oil. We replaced the copper washers and tourqued the injector nuts back down (they were not as tight as they should've been) and stopped the leak. Now all the oil is coming out the blow by tube and the dipstick tube. I'm guessing the rings are shot. Can you replace just the rings? We plan on pulling the engine to fix all the oil leaks anyway so should I also do the bearings? It holds good oil pressure and has 155k on it. Any insight on what I should replace and the best place for parts would be greatly appreciated.

 

[Johnstra]

Couple of things to check before you do rings & bearings. Check for vacuum leaks. The vacuum pump vents into the crankcase and a big leak will pressurize the crankcase substantially. Also, bad turbo seals can cause problems that look like severe blowby.

-john

 

[Vaughn MacKenzie]

Yep, a bad turbo seal lets boost pressure leak through to the oil return line, creating a lot of crankcase pressure.



Vaughn

 

[JBeasley]

How do you check the turbo seal? On the vaccum pump do you just check all your vaccum lines? I did not know the vaccum pump vents into the crankcase. If you have a leak how does that affect how much it vents? I know; lots of questions but thanks for the help.

 

[Johnstra]

I don't know how to check the turbo seal. For the vacuum pump, yes, you just check all the lines. It's pretty easy to check a couple of junctions and narrow down quickly where there's a leak if you have one.

-john

 

[DSahd]

You will know if the turbo is at fault when you see serious smoke come out of the exhaust pipe, as it will leak into the intercooler and exhaust.

 

[JAmos]

My 95 has always had steady oil pressure and the more I tinker with it the better it runs. Im at 210,000 and it looks like oil is leaking from where the exhaust manifold mounts to the head. It had been blowing mostly vapors out the dipstick till it blew the dipstick out. I was thinking that the breather tube was plugged, but Mark at Piers suggested that i have too much blowby for the stock vent tube to handle(due to worn rings). If the turbo is leaking boost into the crankcase would i notice a considerable drop in boost? The only drop in boost came when I ran a new line from the tank to the lift pump last week and i have been having blowby issues for months. I guess i need to look at the intercooler piping and see if any oil has been leaking into them. My 370'sa haze and i gutted my afc so I make some smoke so i never thought of looking inside the piping. Sorry for the long post and thanks for any help.



Jordan

 

[JAmos]

I guess i didn't really post the previous info in a question form, but does anyone have any ideas that back up what I was told or should I look at other possibilities?



Jordan

 

[Vaughn MacKenzie]

Im at 210,000 and it looks like oil is leaking from where the exhaust manifold mounts to the head.

Piers told me a sign of a tiring motor is dampness from oil accumulating around the exhaust port gaskets.

If the turbo is leaking boost into the crankcase would i notice a considerable drop in boost?

No, I think a turbo with a poor seal will not have a noticeable drop in boost.

I guess i need to look at the intercooler piping and see if any oil has been leaking into them.

Jordan

Not sure, but I think you could have a bad seal and not have oil in the intercooler. Not sure about that though.



I was trying to contrive a way to test a turbo for a seal leaking boost into the oil return. Easiest is to probably swap the turbo for a known good one.



The fact you're blowing the dipstick out isn't a good sign. What is the history of the truck, and has it always had good maintenance that you know of?



Vaughn

 

[JBeasley]

Yes, it has always had good maintenance. The truck has been used for a farm truck though. 155k and is bone stock. I ordered a snap-on compression tester yesterday, so I'll know for sure if the rings are shot. Can anyone tell me what the normal psi reading should be and should I check just one certain cyclinder or should I check them all.

 

[JAmos]

I am the third owner and I know very little of the maitenance history. I take good care of it but use it hard. The previous owner did a lot of towing. Thats bout all i know.



Jordan