Will coolant in the combustion chamber cause fuel and oil to not burn on start up?

[m1garand_man]

It turns out that the head on the same bank of my 6.2 which was emitting a cloud of oil and fuel smelling smoke on start up was cracked in each of the middle two intake valves.

The leak was so small that I didn't notice coolant burning at the rate I experienced the last time I had a cracked head so they must have been small cracks indeed. My question is if any of you who ended up finding out you had a head cracked in this manner experienced fuel and oil smelling smoke clouds on start up that cleared up in a few seconds after running.

The reason I am asking this is because I am waffling on whether or not to re ring my pistons and re do the bearings on the rods and crank. I am running out of $$$ for this project and am trying to get confirmation for this fault/symptom to better determine whether or not doing the re ring an re bearing is a waste of money or not. I haven't experienced a loss of power or rough idling until the head cracked which was about two weeks before I tore down the top end of the engine.

 

[cucvrus]

Personally I would just rebuild a set of heads and put head gaskets in. I would not tear into the bottom end just because it needed a head gasket. that is me. Do as you wish. I have changed a couple crank shafts that were broken. I never knew of web cracking until I read it here. So I did not worry about it. I just done the crank shaft change and change the main and rod bearings. Reassembled and was done with the job. life was happy ever after. And to answer your question. A cracked head would of course not be desirable. The smell of oil and coolant would be present. I ran one for a few years with a bad head gasket and at the end it was a steam compressor. Fix the issue and hold off on the major overhaul. Does the rest of the vehicle warrant that expense? When I did mine I had the transfer case and transmission overhauled. The bottom end of your engine is probably fine. But do all the gaskets and seals while you have it out. Or not if you don't have it out. Make any sense?

 

[m1garand_man]

so would tearing down the bottom end be more warranted if there was heavy smoke on acceleration in normal conditions and or loss of power or knocking rather than to just double tap the source of a possible problem likely involving the head?

 

[CUCVLOVER]

If it was my motor.
If It developed a cracked head and the bottom end was good to go I would take care the heads and go on.

How many miles are on the bottom end? How hard are you on the engine? These things come into play when deciding to do a full rebuild or not.

 

[rsh4364]

If you have 10-20lbs oil pressure at idle and 30-50lbs at cruising speed your bottom end is probably fine.If you have excessive oil consumption(not leaks)you may need rings.I would do your heads and go from there.

 

[cucvrus]

I never had an oil pressure gauge on mine. (Mule) But I knew it ran fine and never knocked or burnt oil. So I just done the heads and head gaskets along with all new seals and gaskets. I never checked the oil pressure because it ran so well. I never changed the oil pump either because it was not the issue. it works well with over 1K miles on since i put it back on the road. I changed the rear main seal and the water pump. It runs strong as new. I drive it everyday now. Till it gets real cold. Then the old Mule gets a break and I drive the new Silverado. Hot weather Silverado. Very cold Silverado. Easier on me in the heat with A/C and easier all around on the Mule and me in extreme cold. Magic spray if needed. However only in small quantities over a long period of time. I would just get the heads checked and do the head gaskets and move on. Unless you really like spending money.

 

[Speedwoble]

2 cracked heads? Is the block flat?

 

[o1951]

2 cracked heads? Is the block flat?

Very good point.

Second question - is engine overheating due to poor coolant circulation?
Something is putting undue stress on heads.
In other aps, I have seen heads crack at valves when cooling passages in head had lot of rust/crud/scale, impeding heat transfer, causing localized overheating.

 

[rsh4364]

I never had an oil pressure gauge on mine. (Mule) But I knew it ran fine and never knocked or burnt oil. So I just done the heads and head gaskets along with all new seals and gaskets. I never checked the oil pressure because it ran so well. I never changed the oil pump either because it was not the issue. it works well with over 1K miles on since i put it back on the road. I changed the rear main seal and the water pump. It runs strong as new. I drive it everyday now. Till it gets real cold. Then the old Mule gets a break and I drive the new Silverado. Hot weather Silverado. Very cold Silverado. Easier on me in the heat with A/C and easier all around on the Mule and me in extreme cold. Magic spray if needed. However only in small quantities over a long period of time. I would just get the heads checked and do the head gaskets and move on. Unless you really like spending money.

Rick we all know you like cucvs totally stock,but not all of us have as much experience with these as you do.Gauges help keep the uninformed informed.If this guy had a temp.gauge maybe the head would not have cracked.And if he had an oil pressure gauge he wouldn't be worried about bottom end.Gauges are our friends.

 

[m1garand_man]

If it was my motor.
If It developed a cracked head and the bottom end was good to go I would take care the heads and go on.

How many miles are on the bottom end? How hard are you on the engine? These things come into play when deciding to do a full rebuild or not.

The bottom end has about 38000 miles on it and generally speaking I baby it much to the chagrin of other drivers. My first issues appeared last winter when I made the ill-fated decision to switch to 10w30 full synthetic for the winter and was burning a quart every 300 miles. very quickly oil started to appear in the division between the head and exhaust manifold on the drivers side starting with the #7 cylinder (I think that's the rearmost one) and working its way forward over the winter. I never had oil appearing on the passenger side but I would get fairly heavy smoke on acceleration. When it warmed back up I switched back to 15w40 rotella T and 90% of the smoking went away but I was still burning a quart every 600 miles which is unacceptable to me since in the past I would go twice that distance. Two winters ago while still living in MT I drove the truck all winter with 15w40 in it and since there was no plug ins at work for the pan heater I was starting the truck at -15 to -20 and it would sound very upset at me until it warmed up. That is the reason I felt that the valve train had worn prematurely and was the precursor to all of my other problems up to the passenger side head cracking and huge clouds of smoke on start up out of the left bank.

 

[m1garand_man]

2 cracked heads? Is the block flat?

One head with two cracks. The block and heads appeared flat enough based on the residue from the felpro head gaskets I used which had full coverage on the entire head and block deck surfaces.

 

[m1garand_man]

Rick we all know you like cucvs totally stock,but not all of us have as much experience with these as you do.Gauges help keep the uninformed informed.If this guy had a temp.gauge maybe the head would not have cracked.And if he had an oil pressure gauge he wouldn't be worried about bottom end.Gauges are our friends.

An oil gauge and a temp gauge might not be bad ideas. I know how to do the oil pressure gauge install but I'm not sure if I can just unplug the lead to the current temp gauge on the front drivers side head and just plug in lead for the temp gauge I would install. I don't imagine the stock sensors are too accurate based off the issues with the glow plug temp sensor on the rear of the right head. I ended up installing an override switch for the glow plugs so I could still cycle them from inside the truck when the engine was warm enough to not trip the glow plugs but not warm enough to easily start. My gear reduction starter probably doesn't help with that either as it cranks more slowly albeit with more torque which is good for cold weather starts.

 

[m1garand_man]

Very good point.

Second question - is engine overheating due to poor coolant circulation?
Something is putting undue stress on heads.
In other aps, I have seen heads crack at valves when cooling passages in head had lot of rust/crud/scale, impeding heat transfer, causing localized overheating.

The coolant passages are very rusty. How do I clean that off from the remaining good head?

Is something like evaporust a good product to use? https://www.evaporust.com/cooling-system-cleaner

 

[cucvrus]

Take the heads to a machine shop and they will cook them out and clean them. When I done mine it was $27. per head to clean them. I could hardly stand out in my shop and ponder how to clean them at that price. When I got the heads back after they completely went over them they looked like they just came out of the sand casting. The were lightly rusted from the humidity. I installed them and cleaned them after they were on and painted them. Be sure to use NEW head bolts every-time. That can cause heads to crack if you do NOT use new head bolts. Don't cut corners and try to do things that you are not properly experienced or equipped to do. You may think you are saving money. You are only fooling yourself. The engine will end up costing you more doing it by taking short cuts. Do it right the first time. If you want to cut costs. Spend the money on the engine and doing it right. You can spend money on extra gauges after you have the current issue fixed. All the gauges in the world will not help a poorly assembled engine. You need a professional to check out the heads before you put them on. I do not put a head on anything until I have them checked. At least for level mounting surface. The cost is worth it unless you like a semi annual head changing weekend. Some guys may be into that. Not here. i have other things to fix. It seems rust is trump at this point on customers CUCV's.

 

[dependable]

If you are going to install a temp gauge, I would remove idiot light sensor and install a manual/bulb type gauge.

If wondering about doing the rings or lower end, the oil pressure test is a good idea. A compression test would also be informative.

 

[m1garand_man]

Take the heads to a machine shop and they will cook them out and clean them. When I done mine it was $27. per head to clean them. I could hardly stand out in my shop and ponder how to clean them at that price. When I got the heads back after they completely went over them they looked like they just came out of the sand casting. The were lightly rusted from the humidity. I installed them and cleaned them after they were on and painted them. Be sure to use NEW head bolts every-time. That can cause heads to crack if you do NOT use new head bolts. Don't cut corners and try to do things that you are not properly experienced or equipped to do. You may think you are saving money. You are only fooling yourself. The engine will end up costing you more doing it by taking short cuts. Do it right the first time. If you want to cut costs. Spend the money on the engine and doing it right. You can spend money on extra gauges after you have the current issue fixed. All the gauges in the world will not help a poorly assembled engine. You need a professional to check out the heads before you put them on. I do not put a head on anything until I have them checked. At least for level mounting surface. The cost is worth it unless you like a semi annual head changing weekend. Some guys may be into that. Not here. i have other things to fix. It seems rust is trump at this point on customers CUCV's.

I learned my lesson about cutting corners on just installing as is heads. However on the other hand I have always used new TTY bolts. I will be chasing my head bolt holes this time since they are pretty crudded up and once I am confident my head gaskets have sealed up tight (a tank of fuel) I will flush and reinstall new coolant.

Unfortunately doing a compression test after reinstalling the heads will not be a productive task since if I find out anything negative I will have to tear down the top end again to get the pistons out. This will cost me another $150 in head gaskets and head bolts.

I am going to guess that the rings are probably good since the cylinders measure out at new dimensions which if I am correct should also mean that everything else should measure out about the same assuming everything wears together.

The cracked head leaking coolant into the cylinders seems to be the culprit of my smoking on start up issues. If my rings were going out I think the onset would have been slower than 2 weeks and that the smoking would have been out of both banks not just one.