Engine/Transmission (1994 - 1998) Bubbling Coolant -odd

[98rammer]

... ... ... .

 

[Andy Redmond]

If the rad. and engine are full of coolant the air bubbles may be from a leak caused by a compression loss from the cylinder to the coolant system.



You might also verify this after a coolant pressure test, then by a compression test, the cylinder(s) with low compression are your suspects.



Cummins has a special tool that attaches to the rad. cap and the "dye" changes colors if combusion gasses are entering the coolant system. To further validate if this is the case.



An oil cooler will do this sometimes, but usually puts oil in the overflow bottle too.



Good luck and let us know what you find.

 

[JFaughn]

your cooling system makes 0-18lbs pressure depending on altitude and radator cap, may not make its way to cylinder [yet], cylinder compresion 400-450lbs whitch way do you think that will go? time to ring the head and a good port job , the brite side , now you can bomb it more.

 

[Andy Redmond]

That's what I figured... however, wouldn't it be likely that the coolant enters into the cylinder when the motor is shut off? this would then cause white smoke upon start up and/or a hydrolock within the cylinder.

Maybe or maybe not, I think it can vary. I certainly don't disagree with you of your assumption of where the white smoke comes from. The example of this problem, which I was assimilating to your complaint was that it wasn't a minor leak "out. " I was blowing out 1 gal or so of water each 300 miles. So if it was a little low on coolant, it might not be up high enough in the block/water passages etc to suck it back in. . Or maybe it kinda seals back up when it cools off sometimes. Perhaps it is dependant on where exactly the seal interuption is. . certainly a wonderment.



Do you see signs of "rusty" hard water spots on the oil filter or rubber air intake elbow? Maybe be too soon as it just happened.



If you source a KD compression tester set assure that the adapter no. 6621 (24mm*1. 5 (pitch)) is present or it won't thread into the cylinder head...



Also Joe D has offered an excellent tip in the past about removing an injector at the time to look for a leak in a particular cylinder and looking for a "shiny" clean piston that the coolant has "decarbonized for you. "



If you pull it apart and have time to take some digital pics of what you find, I've love to look at them. -- email address removed --



Good luck

Andy

 

[Andy Redmond]

Rammer:



I would gauge the head bolts and also find a 36" precision straight edge (Central Tools makes one that less than $150).



Carefully ck. the block deck side to side and end to end with the feeler gauges and also the same cylinder head. The specs are in the FSM or Cummins Manuals. .



Use the marine gasket for best results:

3283335 Cummins Marine Headgasket

3283337 Cummins Marine Headgasket . 010 over

3283339 Cummins Marine Headgasket . 020 over



The head bolts are:



6 long ones (rocker tower) 3920781

14 medium ones 3920780

6 short ones (exh manifold) 3920779



Good luck

Andy

 

[Andy Redmond]

opps I hit send too soon

what i gather here, there's a compression leak. once the head/motor warms up, the leak gets smaller as the parts expand. when the big bubbles were appearing, they came is if one cylinder was pushing them through the system. i have a spare stock gasket on hand, but man it's going to suck to do the job.

The fire ring area around the cylinder liner is not sealing well and the compression/pressure point of escape (if our thoughts are correct) is likely the coolant passage near the push rods under the rocker tower for that particular cylinder(s). Other "restriction" coolant orfices exist in the headgasket around a cylinder as well, so a couple of options.



My suggestion of the compression test was to attempt to verify which cylinder so that area can be scrutinzed extra carefully for any tolerance (flatness issues) etc. Since it just happened it may not have much carbon buildup yet.



Tom: I have a picture I can post of what this look like when its been left like this for some time.



How do I post it, I can't attach it (its too large)?



Good luck

Andy

 

[Nyoest]

Checking the head bolts is an excellent idea. We just had a C-12 Cat in the shop, one week it used a gallon of coolant a day and the next week it didn't. Tuesday it had compression in the radiator (HUGE BUBBLES) Wednesday it stopped, but had no heat at idle. Very hard to diagnose changing symptoms but it came out of all of it when we swapped out the streched head bolts



Fwiw



Neal

 

[LWeight]

I was wondering if it could possibly be a bad rad cap also? I just bought a 94' that had been sitting for quite some time. I got it running a couple days ago and when it was first idling coolant started to leak out the cap and a few seconds later it started to squirt out the overflow bottle. The engine sounded just fine idling and it wasn't smoking any more than a normal cold start. My first thought was a blown head gasket but a friend said the cap could be part of the problem also. If anyone could help me out or if my situation applies to the same info above? Thanks for the replies.

Luke

 

[mechanic]

Well, i thought that i had popped the headgasket wednesday night. the coolant overflow bottle is bubbling. brought it down to dad's house, and then to the shop the next morning (oil level didn't change). it started right up yesterday morning before we went to the shop. typically the fluid would slowly (or fast) enter back into the combustion chamber causing a hydrolock or at least a lot of white smoke upon startup, especially overnight. i stoped for fuel a couple miles down the road... Big bubbles in the overflow tank about the size of a nickel or so. get to the shop 25 miles later, little bubbles/foamy.



now, we pressure tested the radiator... leaked maybe 1/10th of a pound after 15 minutes or so. we couldn't be convinced that it was the headgasket. drained the radiator, and refilled with new coolant.



Today, it's still bubbling, but the truck runs fine. there's no white smoke.



any ideas



Tom

It acts like a headgasket seep. They many times will not leak into the cylinders for a long time. One post recommended replacing the headbolts. I would second that recommendation. When there were still some 5. 7 GM diesels (morn) around, I had a number of them that had bubbles in the cooling system, and just locating the broken bolt and changing it out fixed them. No head pull. The Cummins dosn't break bolts but they could strech resulting in a slight reduction in clamping load on the headgasket, which allows a small compression leak.

I have also fixed a number of VW diesels that leaked oil at the pressure port to the camshaft. Only on them I just mark each bolt, remove them one at a time in sequence, clean bolt and hole, apply antisieze, reinstall to the same position as before + 1/4 turn.

Good luck.

 

[JWaters]

I have seen cummings break headbolts up near the front of the head, Put a pressure tester on it and run it hard down the road and back, see if the pressure goes sky hi, We have had alot of 5. 9's leak under boost but not just running easy.