Blowby at idle

J

joelabq

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Dec 6, 2009
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My truck since I bought it was 160k has had steam coming from the blowby tube at idle. I've never figured out why, but even if I pinch off the Vacuum line at the pump it does not change. I will only lose oil if pulling at high rpm.

I stopped the oil loss a couple years ago by putting a vent up off the oil fill tube with a barbed fitting, some JB weld, and some 1/2 hose. I never really lost oil (maybe 1/2 quart in the catch bottle I had or so over 10k miles). I got tired of the steam being up front and varnishing the engine bay so I capped and moved it back. I tried putting in a home-made seperator, but it did not flow enough and caused me to cover my fender with oil blowing from the dipstick tube. I ditched that. Now I've been running the vent I made and the stock tube for a month or two, but after a hard run it just hazes at idle and it drives me nuts.

Today I received one of those dual valve cover breathers and replaced two valve covers with this device. I plugged the other two breather tubes. All this device did was move the haze up to the top of the motor. After idling for a few (truck was cold) it started the hazing again, and within a few minutes I could stick my finger in the vent hole and wipe out oil onto my finger.

What is odd is that if I rev up the motor I can feel the pressure become less, and then as it falls back to idle the pressure increases. I pinched off the vac hose again and no change.

It looks like steam, no blueish tint, looks like a tea pot on the stove blowing steam out of the spout.

I don't get it?! I am tired of this but I'm in over my head on this one. Any ideas? Truck runs great and tows my 10k# 5th wheel no sweat. 30lbs of boost and cleans up nice if you stomp it.

Joel
 
It means the rings aren't sealing as well as they used to...so you have a lot of blow by. Either learn to love it or rebuild ther motor.
When it gets really bad it blow the oil fill cap out of your hand when you uinscrew it while it's idling. LOL
 
Wouldn't it have a blue tint if it was rings? And does that make sense if it appears to have less when revved up?

I remember asking around about rings before at a couple local shops and they all said with the miles I had (160-170k) their should be no reason for it to be rings. Seems odd still. Truck hardly towed anything until I got it.

My dads 2007 CR has a similar haze if you take off the oil cap although slightly less, and it has 107k. Are rings that common of a problem?

Also, if it is rings, any way to do an in-frame ring replacement if the cylinder walls aren't scored, or do I HAVE to remove it? I don't have a stand for something this heavy!

Joel
 
Large vacuum leak would be a possibility. With no leak the pump is dead headed and a large leak will let it pressurize the engine. Don't think it could cause that much oil loss though. I've been wrong before too.
 
You can do an in frame if you can remove the head and pan which is not an easy chore. Don't think you could get a hone to the last two holes either.
 
how are you goig to get the pan off, and i wouldnt do it with the crank in.

you could hone it from underneath, but might as well just pull it
 
I pinched off the line right after the pump. No change in blowby. The only thing that reduces it is to rev up the motor.

Oil loss isn't that great unless I use the stock location, then it's about 1 qt every 200 miles or so if hauling heavy.

Joel
 
harbor freight has a nice 2000 lbls engine stand for $119 dollars, I just pick me one up before i put my motor back togather, been the 1250 lbs stand didnt like the Cr hanging off of it.
 
Before I consider this a done issue of rings, whats the proper way for diagnoses? Should I just take it somewhere for a leak down since I don't have the tools and hopefully won't need them often?

Joel
 
if its not the vac pump leaking the motor needs to be gone through, might as well save the money for doing the reman.
 
joelabq said:
Before I consider this a done issue of rings, whats the proper way for diagnoses? Should I just take it somewhere for a leak down since I don't have the tools and hopefully won't need them often?

Joel
Click to expand...

Yeah, before you start tearing things down do some diagnostic work. If you don't have a trusted shop it wouldn't be a bad idea to have a couple different shops give you their diagnosis and quotes.
Try doing a compression test. If its low, pour a little oil into the cylinder and redo the test. If compression is up the rings are bad.
 
Does it matter who does machine work on these things, or any trusted machine shop good enough? Also, whats a good source for rings (and pistons just in case)? Any other things one should do while in there?

...or should I just look for a used/yanked out engine with a warranty?

Joel
 
Any good machine shop should be able to do the work.

Talk to Snedge on here about getting parts: Mumau Diesel - Competition Diesel.Com - Bringing The BEST Together

Have the cam drilled and tapped for a retainer while you're in there, or just get an aftermarket cam. And if you think you ever may want to run twins or make a lot of power have the head O-ringed and look into studs.

It your call it its worth rebuilding or replacing with used. If you plan to keep it or have big goals in mind you could rebuild to a more power ready/durable combination.
 
A bad turbo seal can be a source of blowby, but more likely would cause the inverse of your situation and increase with RPM and boost.
 
I would definately say with more boost theres more blowby. Would oil pressure being higher than boost pressure cause it not to blowby until higher boost levels?

Lets say I want to eliminate this possibility, what would be the best way? Pull turbo and run it open manifold (neighbors will love that one!) or something else?

Joel
 
joelabq said:
I would definately say with more boost theres more blowby. Would oil pressure being higher than boost pressure cause it not to blowby until higher boost levels?

Lets say I want to eliminate this possibility, what would be the best way? Pull turbo and run it open manifold (neighbors will love that one!) or something else?

Joel
Click to expand...

I'd like to know this also
 
i have really really bad blow by on my truck. my motto now? drive her till she blows :) i would say just drive it imo
 
It wouldn't bother me so much if I didnt have drivers constantly "letting me know" that I've blown a rad hose or that theres smoke coming from the bottom of the truck.

Joel
 
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