Blown head gasket or something else?

[Don-T]

Hi everyone, I hope its ok to revive an old thread. I have a little more time to look at this M1009 now. I pulled the thermostat housing and thermostat. I also pulled all the belts off the accessory drive. I then filled the crossover up to the top of the thermostat housing with antifreeze. I started the engine and watched. Nothing at first but after about 30 seconds bubbles started to come from the driver side head. None from the passenger side. That gives me a starting point.

Now to start some research. Someplace I read a procedure for pulling heads without needlessly removing parts. I don't remember if it was on this site or another one.

 

[cucvmule]

Welcome Back!

After sitting did the engine labor to get stated, having any fluid in the cylinders can hydrolock the cylinder as fluid will not compress and some of the time can crack the piston lands between rings trying to relieve pressure to get piston cycling.

Having air bubbles in the system after sitting is normal, and adding fluids may have had trapped air in the system. I would put the water pump belt on and throttle up a few times to try and purge the system of any trapped air. But getting all the air out from just idling will be hard to do.

 

[Don-T]

Thanks for the input. After sitting for anywhere from a day to a month it starts as though there is nothing wrong. I don't think any liquid is getting into a cylinder. I have been trying to get air out of it by driving it off and on for about 8 mouths now, hoping there was air stuck in there somewhere. I no longer think that is possible.

I am beginning to think this is a cracked head. The reason being the bubbles show up about 30 seconds after the engine starts, compression pressure pushes past a crack and into a cooling passage and starts to build pressure. I think it takes that 30 seconds to get to the thermostat housing and a bit longer to show up in the radiator and then past the cap and into the overflow. As pressure builds it pushes coolant into the overflow tank. Once pressure is built up and the engine is shut off compression pressure in the cylinder is gone and the pressure in the cooling system is not enough to push back through the crack into the cylinder. The cooling system stays pressurized at whatever the cap can hold it to until I vent it. I think if it were a head gasket it would be more likely to not keep the cooling system pressurized the way it does. I may be way off but maybe it will give someone a clue as to what is really going on.

Here are some symptoms.

Steady stream of small bubbles when the engine is running. Doesn't matter if it is cold or hot. Thermostat or not. I just removed the thermostat and belts as described above and the bubbles are coming only from the driver side head.

When the engine is running with everything hooked up ut pushed coolant into the overflow bottle to the point the overflow bottle overflows and low coolant lights comes on. I won't let it run past that as I don't want it to overheat. I has not done that to my knowledge.

The coolant temperature fluctuates quite a bit once it warms up.

It starts as it should cold or hot.

Sorry for being so long winded on this.

it runs as it should cold or hot.

It does not smoke at all cold or hot.

With the radiator cap on the system builds pressure and holds it for weeks at a time.

There is no oil in the coolant.

There is no coolant in the oil.

I am almost sure I have either a blown head gasket or cracked head.

 

[dougco1]

My money says cracked head or heads and not the gaskets; oh wait, it will be your money.

You need to pull the heads and by default you will be installing new gaskets anyways.

Drop the heads off at a reputable shop and have them checked.

 

[Don-T]

Hey guys, hope it's ok to bring up my old thread. I just did a compression test on this. I did it on a cold engine, I know it is not the best way, but I am not up to working on a hot engine. Here are the results:



I am surprised several cylinders are as high as they are.

In addition, a couple of weeks ago, I pulled the accessory belts and the oil fill breather. I started the engine and checked for blowby, there was virtually none.

I should add: all this is in addition to the steady stream of air bubbles in the cooling system coming from the driver side, likely either head gasket or cracked head.

Any and all thoughts are appreciated.

 

[CARC686]

You can put a little oil down #4 and if the compression jumps up, then you know it's not a valve.

 

[Don-T]

You can put a little oil down #4 and if the compression jumps up, then you know it's not a valve.

Normally I would but the heads are coming off anyway. I was hoping one of the cylinders on the driver’s side would be way low showing a bad head gasket but that didn’t really happen. I think maybe a bit more indication the driver’s side head may have a crack into a cooling passage.

 

[CARC686]

Can stick a bore scope in the plug holes to see if you've got a steam cleaned piston before taking it apart. Fluorescent penetrant dye could be helpful.

 

[Don-T]

I thought about doing that but decided against buying a bore scope to look and just pull the heads for the a couple of reasons. I don’t see any evidence of blow-by. I have no smoke out the exhaust, either side. I don’t see any sign of contamination in the oil. The engine does start and run good, even in the cold winter.

I do have a steady stream of small bubbles in the coolant coming from the driver’s side head. The cooling system does get pressurized when the engine is run, and it will hold the pressure in the system for weeks.

It just occurred to me, I do have a leak down tester. If I can find a way to make it fit either the glow plug or injector port I can maybe find out which cylinder or cylinders are leaking into the cooling system.

 

[87cr250r]

You're symptoms are exactly what happened to mine. It ran that way for a few thousand miles and then started getting worse quickly it blew out the water passage at the end of the head gasket, that's where almost all of these go.

Option 2 is a crack between valves. I have seen these pinned. I have one that I don't think was pinned correctly so I have a leak from that one. It's only exhaust port pressure. This leak doesn't build and hold pressure for months like the head gasket did. It behaves normally other than the bubbles when the cap is off.

 

[Don-T]

I started to take the top of the engine apart and looking at it I am wondering if it has been apart in the past. It doesn't seem like the intake manifold gaskets are OEM to me. What do you people think? They are surely leaking. I am guessing except for allowing dust to get in it doesn't really affect the way the engine runs. I noticed two of the intake manifold bolt holes near the front are full of oil, don't know if that means anything. None of the intake bolts had any kind of sealer on them. The oil the valley and down the back of the engine was coming from a leaking CDR hose where it connects to the intake on the driver's side.
-+

 

[87cr250r]

The intake bolts should not have sealant.

I do see silicone on the water manifold gaskets which should not be there.

The fuel supply hose is certainly not original.

The manifold gaskets are marked like Fel-Pro but the don't have the plastic locating pins on the ends.

 

[Don-T]

Do people use any kind of thread locker when putting these back together? It seems as that they should have something. Is the compression of the gasket enough to keep the bolts tight?

 

[Don-T]

I have another question. Did the injection pumps have the bar code tags on them in 1986? I don't think so.

 

[87cr250r]

Mine did and I'm very confident that it was original.

 

[Don-T]

I have the heads pulled off now. The engine has the PrintOSeal head gaskets in it. Are those the head gaskets I have read are not reliable? I do not see a single one of the dreaded cracks in either of the heads. At least that may be good news. The way the head gaskets came apart I don't see an obvious failure but but that doesn't mean anything. Here are a few pictures.

 

[Don-T]

I am going to call a local machine shop I found on the internet to see if they have any experience with these 6.2 heads. I would like to get them checked out. Maybe they are ok and I just need new gaskets. does anyone have part numbers for known reliable head gaskets for these engines? What about where to buy the other top end gaskets I will need to put this engine back together?

 

[CARC686]

FEL-PRO MS91585
FEL-PRO 8726PT

 

[nyoffroad]

I am going to call a local machine shop I found on the internet to see if they have any experience with these 6.2 heads. I would like to get them checked out. Maybe they are ok and I just need new gaskets. does anyone have part numbers for known reliable head gaskets for these engines? What about where to buy the other top end gaskets I will need to put this engine back together?

Get a new set of head bolts too, sucks but they are single use only.

 

[dougco1]

I have the heads pulled off now. The engine has the PrintOSeal head gaskets in it. Are those the head gaskets I have read are not reliable? I do not see a single one of the dreaded cracks in either of the heads. At least that may be good news. The way the head gaskets came apart I don't see an obvious failure but but that doesn't mean anything. Here are a few pictures.View attachment 927688View attachment 927689View attachment 927690

Cracks sometimes are hard to see. Hopefully the shop will give you good news. They may have to be shaved down to true flat again.