Coolant out of blowby tube

R

regcanfan

Member
First post here, I hope its ok to ask a question. I have a 97 3500 and I'm getting some vapor and a few drips of antifreeze out of the blow by tube. It only appears when it warms up after the thermostat opens. The bottom of the oil cap and visually the oil both look clean. The pickup was all stock up to about 1000 miles ago. I ground the fuel plate and did 4k governor springs. When I redid the head i out in 5x.011 injectors. It only has 135k miles on it now.

I just replaced the head gasket thinking this was the problem. I had the head checked out, surfaced and gone through. Used new stock head bolts torqued to 130 ft lbs and a thicker gasket.

Kind of stumped I'm wondering, would it be a crack somewhere in the block or could a bad oil cooler cause this. The motor runs smooth with no missing and isnt down on power.
 
I have seen a a small crack happen between freeze out plugs behind the the push rod cover before. Can’t say I remember seeing coolant come out of the blow by tube. We got bad samples back for coolant in oil. Replaced/tested oil cooler can’t remember if we did a head gasket or not. Just remember finding that crack. Had a guy come and loc-n-sitch to fix it.
 
I need to check if there is any oil in the coolant. I did check thd the oil fill cap and although it looks clean if I wipe the bottom side of the cap off the residue smells and tastes like coolant.

Would it be possible to have a crack in the cylinder wall and not have a miss or pressurize the cooling system.
 
regcanfan said:
I need to check if there is any oil in the coolant. I did check thd the oil fill cap and although it looks clean if I wipe the bottom side of the cap off the residue smells and tastes like coolant.

Would it be possible to have a crack in the cylinder wall and not have a miss or pressurize the cooling system.
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I would put dye in the cooling system, which would transfer to oil if its getting in the oil and pressure test the cooling system. it should hold pressure overnight. If the issue is more noticeable when engine warm id ad the dye, run the engine until it reaches operating temp, and then let it sit while under pressure.
 
I'd send in an oil sample for analysis. Yes, there have been instances of blocks cracking in the cylinder walls.
 
Not saying the oil cooler isn’t a possibility. But usually if an oil cooler is bad you will get oil in your coolant instead of coolant in your oil. Oil pressure is higher than coolant pressure therefore unless your cooler is completely screwed up your oil pushes throw the crack into the coolant.
If it’s bad enought yo might get coolant to push through after truck is shut off because coolant will hold a little pressure for some time where the oil pressure drops right off immediately. But you should still get oil in your coolant if the oil cooler is cracked.
 
I'm going to test the cooler first and put in new gaskets, I think they are about $60. If it checks out ok I guess I might have to find a block, or is there ways to fix a crack.. Been doing some reading and it seems like there has been some others with cracking around the push rod area as stated above.
 
I guess Mr. Nixon is just down the road from me (not sure if he has any right now), or I suppose there are lots of blocks around worse case scenario. It to nice to just trash. Is a 97 reg cab 3500 cab and chassis 2wd with only 133k on it with a perfect body and paint and flatbed.
 
regcanfan said:
I guess Mr. Nixon is just down the road from me (not sure if he has any right now), or I suppose there are lots of blocks around worse case scenario. It to nice to just trash. Is a 97 reg cab 3500 cab and chassis 2wd with only 133k on it with a perfect body and paint and flatbed.
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What's this "Mr." stuff? :D

I have 3 blocks, 2 are bare and about to hit the iron.
The third is a '96 short block that had a valve roam around in 1 cylinder.
It destroyed the head and piston, but it doesn't appear to have hurt the cylinder.

I will sell any of them cheap.

Mark.
 
The gaskest for the oil cooler comes in tomorrow so maybe this weekend I'll check it out. Probably wasting my time but i guess I'll give it a try.
 
GAmes said:
I'd send in an oil sample for analysis. Yes, there have been instances of blocks cracking in the cylinder walls.
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#5 &#6 will get cracks very fine cracks if you were to bore the block 20 over. Lucky cummins made solution for that they sold iron cylinder liners #3904166 or part 19 on diagram.
 

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I still haven't had time to check the oil cooler ( I'm thinking it will be a waste of time but still want to rule it out). If its a cracked block what would you guys think abo uh t finding a bare block and swapping in my mind crank and pistons and cam. Obviously would i put in new rings and bearings. Or is this a bit risky using used parts.
 
I don't see any risk. The majority of rebuilds reuse the cam, crankshaft, pushrods, lifters, etc. If the pistons are in spec and undamaged, why not?
 
Nothing wrong with used parts but I wouldn't jump straight to a cracked block. We have seen many oil coolers and head gaskets cause coolant in blowby tubes. It can steam out of the oil and condensate in the tube.
 
Thats reasuring I did buy a new cooler but like i said before just need some time to get it in. I know the head and gasket is good.
 
Well got the cooler in and it does the same thing so...looking like a cracked block like others stated above.

Now its time to decide what to do. Thing about finding a block and swapping over my bottem end parts. Or would i be better off finding a new or a good used short block.
 
Run it bud, a few drops of coolant isn't going to hurt anything, you said the oil is visually clean, save your money. Build a catch can for the tube and call it a day.
 
I don't understand how you can have coolant coming out of the blow-by tube, but not have coolant in your oil ????
 
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