Coolant explosion on the M817 today

[greenmountainmarine]

Hey everyone, just decided now that we are shut down to pull the 817 in to the shop today and start doing fluid change/filters. I haven’t started it since January but fired right up, warmed up for 5 min and then drove it it 1500ft up the road to in-front of the shop. At that point I shut it down because I was smelling something. Looks like coolant was exploding everywhere from the expansion tank. I gave the cap a twist to make sure it was shut and when I cracked it open a hair coolant came pouring out. What do you think head gasket got it possible air bound? I’m a Detroit guy so this 250 might have some shuttle nuances I’m in await of? Had the truck two years with no issues of this nature.

thanks
Lucas

 

[Scrounger]

Possible head gasket. Maybe oil cooler, caught just in time. Check the coolant in the tank. If there is any oil in it, if it looks likes chocolate pudding, then it is the oil cooler. A simple test for a leaking head gasket is with a surgical glove. With the coolant reservoir cap off start the engine. Grip the open end of the glove around the reservoir opening. If it inflates, then a head gasket is probably leaking.

 

[74M35A2]

Could a blown air compressor gasket do this as well?

 

[greenmountainmarine]

Update.

Well Something bad has happened. Next morning put a glove on and went to start. Got about 1/3 a revolution before the engine locked up. Pulled the oil pan drain and about 2 gallons of coolant came out then oil. No oil apparent in the coolant... so i'm going with head gasket or worse cracked head. filled one of the cylinders with coolant. Pulling heads as soon as I finish the boat thats in the shop today.

 

[Ajax MD]

That sucks. Hopefully just a gasket. A pressure test will hopefully reveal the leaky head.

 

[greenmountainmarine]

Ok we got into it today. Coolant in cylinders 3,4,5 and 6. Looks like the #2 cylinder has a leaky injector. but no obviously bad head gasket? coolant looked oil free but gallons of coolant in the oil pan. Ideas? warped head? are these wet liners?

 

[greenmountainmarine]

Ok we got into it today. Coolant in cylinders 3,4,5 and 6. Looks like the #2 cylinder has a leaky injector. but no obviously bad head gasket? coolant looked oil free but gallons of coolant in the oil pan. Ideas? warped head? are these wet liners?

 

[Ajax MD]

View attachment 797181

Yes, the engine is wet liners. Did you drain the coolant system prior to removing the heads? I'm trying to understand if the coolant on top of the pistons is spillage from the heads when you removed them.

Ok, no oil in the coolant, but coolant in the oil pan.

@simp5782 @Scrounger- any help for this gent? Is there a way to test the oil cooler for leaks?

 

[Scrounger]

A blown head gasket will pressurize the cooling system as described. When an oil cooler fails there is usually oil in the coolant as opposed to coolant in the oil. The oil pressure is higher than the coolant pressure.

The question is how long was coolant in the oil? Coolant destroys crank bearings. The best approach is to remove the oil pan and see what it looks like inside. One can look at the liners and see if anything has been leaking from below. For piece of mind it would be a good idea to pull a couple of the bearing caps to see if coolant has eaten them up. If the head gasket(s) just started leaking coolant, the bearings look OK, then it is probably just head gaskets. It wouldn’t hurt to take the heads to a machine shop and have them checked for flatness. If you don’t have one, see if you can borrow a straight edge to check the block deck.

 

[WillWagner]

Could have been just leaking coppers. Head gaskets will not put coolant in the cylinder but will pressurize the cooling system, more so with the new style head gaskets that have the rubber water passage seals. Shoulda pulled the injectors and pressured the system before tearing down. I don't like the new pic adding thingy, you can't enlarge the pics. Looks like all of the water grommets are adhered to the deck. Did they rip in half, half on the deck, half on the head? You pulled the heads off OVER the push tubes?