Blown Head Gasket - Diesel Forum

capt324 · 08-19-2008, 07:02 PM

I pulled the engine out of the 1989 F350 with an 7.3 IDI I bought because it had no compression in the #6 cylinder. I knew this when I bought it an figured it was a blown head gasket. The truck was basically given to me so I couldn't pass it up. After tearing the motor down I found that it blew a head gasket above the number six cylinder. Is this a common problem with these engines? I am new to Diesels. Also, at this point I am going to finish pulling the engine apart to check everything else. The engine has 160,000 miles on it. The cylinders look great an have virtually no ridge at the top. I am looking for recommendations, should I tear the whole thing apart or just roll some new bearings in and put the bottom end back together? I was going to tear it down and have it honed and replace the rings. Is it possible to do this or should I have it bored out and replace the pistons? The number six piston did get a half moon on it from the part of the head (not sure what it's called) where the injector port is. The fuel entry hole part of the head dropped when the head gasket blew out and the piston touched it. Nothing bad, but it did touch. Of course I am having the heads redone but was just curious what you guys thought about the bottom end. I am trying to do it right but at the same time do not want to spend a ton of money unless it is necessary. This truck is just used for towing my camper and race cars. Any input would be a great help. Thanks.

cdnsarguy · 08-19-2008, 08:47 PM

Sounds like the precup may have dropped onto the piston..... was the head gasket destroyed in that area..... it is what holds it up. If the protrusion/recession of the precup is more than .0025-/+ there may be part of the problem.

160K is not even broken in yet....... so honing and rings is not required..... can you see the crosshatch on the cylinder walls.

The bottom end is most likely cherry...... but your choice as to what you do.

If your getting the heads redone ensure they are done to AERA/Navistar specs any milling of the head surface can screw them up.

Cucamongan · 08-20-2008, 04:14 PM

Pictures?

I just got done doing the same exact thing, blown head gasket Cyl # 6 at 152K(?) miles

I have pictures here: 1988 Ford F-250 Replacing Blown Head Gasket @ 152K(?) miles pictures, videos, and sounds | SuperMotors.net

also, replace the oil cooler seals/gasket/o-rings while its out. right guys?

capt324 · 08-21-2008, 02:32 PM

Thanks for the input guys. Yes, the gasket blew out right at the top of the cylinder so that is why the precup (now I know the name) dropped and the piston touched it. Again, it only touched slightly but did make slight marks in the piston. On a gas motor I would not have any second thoughts about using this piston but with the compression on a diesel I was just worried that the piston would fail. You can see some crosshatches in the cylinders still, not all over but some are still visible. Also, as I mentioned there is virtually no ridge at the top of the cylinders. I think since I am this far I may as well just pull it apart and send everything to my machine shop to check the rods and pistons over. I'll have them clean the block and put in new cam bearings, check the crank and if possible just hone the block so I can reuse the pistons and just replace the rings. I'll put in new bearings and put her back together. No sense in having to pull the motor back out again. It wont cost too much to do this and I figure it will be worth it. The truck should run forever after that. I only use it for towing and hauling purposes which is not too often. Is there a rebuild kit for the oil cooler? I do not have it off the block yet so I haven't checked it over. Also, is it normnal that the shop will replace the precups when redoing the heads? Only one came out. The rest are still in the heads. Mine all seem to be worn (slight cracks) at the openings. Thanks again.

bill6ft6 · 08-27-2008, 10:17 PM

just joined. bought my son a 92 f250 hd supercab. truck is pretty clean, 200k, but the owner was very meticilious on keeping a reliable running truck. lots of parts replaced. his buddy was a ford mechanic. runs great.
now for the big question? what is causing this head gasket problem? i had a northstar engine and i know oh so well of those problems. should the heads be retourqued? coolant problem? how could i avoid this problem? all suggestions are welcome.
thanks
bill

capt324 · 08-28-2008, 09:31 PM

Not sure as I am new to Diesels but I was reading on a couple sites that one fix for the head gasket problem with the IDI is to use the Fel-Pro head gasket instead of the stock type. Apparently the Fel-Pro's are supposed to be stronger from what I read, especially in the area where mine blew out. Not sure if this is fact or not but when I put my engine back together (after I get all the parts back from the machine shop) I am going to try them. I figure it can't hurt. Does anyone out there know if this is true or not?