I have been through many of the threads and would like to post here to get some experienced responses to my issue and advice on path forward.

My son and I rebuilt a 93 F350 that he bought for his first truck and we completed everything a little over a year ago. below is a picture when we put the engine back in.



We did a complete rebuild on the engine and had it sleeved back to standard size. It has been running great for a little over a year now, but we have recently encountered some problems. About a month ago it overheated on him and we were leaking at the top coolant neck on the engine and it was blowing out of the radiator cap. We replaced the radiator (still under warranty), the cap, the thermostat, and gasket on the thermostat neck. It did great for about five or six trips to school and then it was running hot again. It started leaking around the heater box. That leak stopped and now there is a slight run of coolant from somewhere on the front of the DS head. I cannot see exactly where, but it is running from just above the oil cooler. At first I thought is was leaking from the oil cooler, but later determined it wasn't.

Now - here is what I have diagnosed. My coolant system pressure almost instantly goes up to about 16 psi after running for just a few seconds. There is pressure and overflow out of the overflow canister. I have a slight sick/sweet coolant smell coming from the exhaust, but no white smoke like is inherent of a blown head gasket. The oil is clean and not milky and likewise there is no oil in the coolant. It does not seem to be running rough or any different. My assumption here is that a head gasket has fouled and I am getting compression leaking into a coolant port. I did have a shop do a test on the coolant gasses and he said there was no (carbon ? I think it was) in the coolant.

My path forward was to pull the engine and take the heads off and have them double checked by the machine shop and of course replace the head gaskets.

The question in my mind here - could this be anything other than a head/head gasket issue and should I explore beyond the top end. When I pull the heads will it be obvious to the novice eye that it is a blown gasket.

One thing to add here - my son did confess that about a week before all of this started - he was keeping his foot in it out in some mud with some friends - so I am guessing this failure was a result of that stress on the engine.

 

Overheat the engine and the gasket wiggles around, sounds like it pushed out and you have a path of combustion pressure making it into the coolant passage. Remove both heads and view carefully the gasket, also look for sleeve movement, if you did all 8 you may have issues there.

Javier

 

The machine shop did sleeve all eight - so you are saying that sleeve movement could possibly be a problem - to understand - if there was sleeve movement - it would have compromised the head gasket - correct?

 

Well yes this happens, I had to sleeve my block also but just one hole. Don't sweat just yet.
Pull the heads clean them up, put a flat edge on them check for straightness and very carefully inspect the gaskets, you will see the root cause of the leak.
But you really need to see if the block deck is still smooth and you should not see any sleeve pushing up.
Most likely you overheated it and popped a gasket, this engine is non turbo? make sure you buy new head bolts, $100 on ebay or buy a set of studs, about $400


Javier

 

It is non-turbo, BUT - we have, with this latest expense, decided to add the Banks Sidewinder package once we have it back in and running. I was planning on doing the studs as I did on my 97 7.3 and 07 6.0 - just for the added insurance and peace of mind. One added question - if I use the studs - they will help align the head - can I remove the dowel pin sleeves for the head alignment (there were two on each side - do they serve any functional purpose other than aligning the head?) - We had a heck of a time getting the head gasket around those when we assembled it originally. I, at first, thought that might be our problem because the gasket tore just a little on one of them, but they are further in on the deck and I would think I would have more fluid transfer oil in coolant or coolant in oil if the gasket failed at one of these points.

 

You could also Have a cracked head. The gasket leak at the head could be the result of the High coolant pressure. Make sure to have it checked when you have it apart.

 

I was going to have the machine shop re-check the heads once I have them off.

Can you tell me if the High coolant pressure could be caused by anything other than combustion leaking into a cooling port. This is my concern - I don't want to pull it out and only work the top end of the motor if there is something else somewhere that could be causing the high pressure in my coolant system. I was just assuming that all of the leaks were sort of the weakest links, so to speak. As the pressure built it was spitting at the weakest points that could give it breathing room.

 

What I would do is start pulling a glowplug at a time and find out which cylinder is pumping up the coolant, no glowplug = no compression, if it gets a high pressure in a few seconds, you don't even need to run it, just crank it over till it starts pissing coolant do this till it stops and you found the offending head and cylinder. At least this gives you an idea where the problem is.

And only the cylinder wall (pin hole leaks, not likely with a sleeved block with low miles) or head/head gasket can cause this issues, so no need to worry about the bottom end.

 

Ya.. With a sleeved rebuild I would say its most likely a head gasket or a cracked head. with pressure building very fast it seems to me a head gasket leak to the coolant passage is first on the list...doing a pressure check by removing a glow plug and cranking (disconnect the fuel shut off) this will show you the cylinder that is the problem like ifrythings said...then you know where to look when you disassemble. If the engine has been consuming coolant then you need to check for cylinder wall scuffing most likely you will be ok if only combustion gasses have been pushing into the coolant passage and not coolant into the cylinder.