Heads and Gaskets, what are the final rules? Story included.

[john8662]

Question for those who know..

In my taking apart the engine that came out of my recently acquired 82 diesel truck I discovered many many problems with the engine. One of which was a blown head gasket, and others include 3 broken plastic retainers on the rocker arms (later type).

Hmm, this ain't no 82 model engine, more like a 91 model (its weird in that it has a turbo oil feed plug in the front of the block where 6.5 turbo's get their oil) yet the block says in bold "6.2L Diesel" and is a 660 block not 599. Anyways, I also discoverd that someone installed 6.5 heads on this engine, the previous owner had supposedly "never got it running right" and had put heads on the engine (so I was told).

I know why it didn't run right now because of obvious loose injectors, bad wiring, poorly torqued head bolts (wasn't hard to remove em) and the junky later model rockers with the plastic retainers (better way???? NOT!)

So, I am going to try and put this engine back together (since it looks as though it'll actually run if I put it together right). I have never had this truck running, and am glad that I didn't try. Mainly because of the sludge I drained out of the oilpan (grey almost like light grease, smell = horrible). So I am assuming that it had antifreeze/water mixed in the oil from the heads. I didn't see any cracks in the bottom webs of the engine, I still need to take a closer look (usually water in oil = busted block right?).

First question, since I have the heads off I noticed rusting of a few cylinder walls (light, but they ain't shiny in a couple of cylinders). Should that be of conern, or will the rings bite again and clean em up? I really don't want to do a full rebuild now, as I will later with a set of 19:1 pistons (project in mind, saving 4 now).

Second question, I am thinking of putting on the 6.5 gaskets with the 6.5 heads, but I already have a set of 6.2 gaskets on hand and another set of 6.2 heads (82 heads though). Should 6.5 head gaskets be used on a 6.2 engine when using 6.5 heads? I believe that (according to crew84) that we should use 6.2 gaskets with 6.2 heads. So what is the consensus? Or would there be anything wrong with using the 6.2 gaskets with the 6.5 heads?

Thanks!

[crew84]

The 6.5L Felpro head gaskets are the better gaskets. They are thicker. The problem with sealing that I had was because of the earlier 6.2L heads. They had a water passage in a place that your 6.5L heads do not. You really need to get JIm's Book on rebuilding. The head bolts are special and can only be used once. I suspect that the head bolts you removed were used again...not a good idea! As for cracks in the block you are going to have to remove the main caps to do a complete check. The cracks start at the bolt holes of the mains on the block. They have nothing to do with water rather they break the main bearing support on the block itself.

[john8662]

Yes, I am aware of needing new head bolts. I already have a set. About the cracks, I have taken apart two other 6.2's that I had just to see what happened why they quit running. One of them was cracked bad enough to see the cracks running up to the clylinder walls, and then getting into the water. So thats why I ask if there is somewhere else in the block prone to cracking that could cause water in the oil. I was under the impression that the usual blown head gasket meant compression into the cooling system. But sometimes it had gotten into the oil. I will also get the rebuild book prior to doing a full rebuild on this engine, but for now, I just would like to have it running to have a backup truck for when I tear down my 86 6.2 and install timing gears and other items. Need a truck, because my suburban ain't got a bed.


Anyone else on the gaskets? will my 6.2 gaskets work with the 6.5 heads? I am leaning towards a set of felpro 6.5's now.

[JeepSJ]

Also, since you found that nice gray sludge in the pan, you should pull all the mains and inspect all the bearings. It wouldn't be a bad idea to inspect the rod bearings while you are in there. Probably wouldn't be a bad idea to add a main girdle at this time too.

[john8662]

JeepSJ,

Thanks for the suggestion. The first thing I did when I got the engine out of the truck and onto the engine stand was pull the pan. I wasn't gonna waste any time on this engine if it had a cracked bottom end. I am really torn about putting in the stud girdle kit in this engine. I already put one in my 95 suburban. But since the 82 truck is just being put on the road for awhile with a rebuild in the near future I don't know if I should spend the money now. I pulled two of the main bearing caps on the engine, the very front one and the middle one, I will still pull the rear main one later to put a main seal in later. But surprisingly, not bad at all (visual inspection, no plasti-gauge) crank wasn't scored. Haven't pulled any rod bearings though, might pull one just for grins.

Main things that worry me now are just the rusty cylinder walls on a few holes.

Anyone replace just the plastic retainers on the rockers? Are they sold individually? I might (yeah I'll get boo'ed) install the 82-84 solid rockers in place for the time being, not too sold on the pressed ones held by plastic.

[rickmeyer]

the rusty cylinder walls tells me that the head gaskets failed, and as long as it didnt hydraulic you probably wont find cracks in the block. I bought a 93 TD that blew a head gasket pulling a hourse trailer at 70 mph, hydralic'd #1 cylinder and busted the rod into 3 pieces...didnt crack the main webs. If the rust you describe is very light, like you could rub it off with your oil dipped finger, you could get away with a hone job. I've used a 3 finger stone hone attached to an electric drill with good results. the real trick is getting the cross hatch pattern on the cyliner walls. A qualified engine machine shop can hone the cylinders also, and if youre palnning to re-ring That would be my recomendation. Good luck!

[john8662]

rickmeyer,

Thanks for the idea on the hone, I had a friend mention for me to use a three finger hone too, sounds like a plan to me. I am waiting till next paycheck to get some headgaskets and some other items to put this thing back together. I am not gonna re-ring it just yet, I want to use the truck for a little while even if it uses some oil and has some blow-by. Because a complete rebuild will be in the future, just don't know how soon.

[ 08-27-2004, 09:33 PM: Message edited by: john8662 ]