new user here, with blown head gasket

[wstukas]

Hello all. This is my first post here (and sorry it is a lengthy one) although I've lurked around reading some stuff as a non member.

I have a 94 4x4 Sub 6.5 TD that serves as a daily driver/tow rig for my race car(s). Currently has 308,000 miles on it. I've installed a Heath manual boost controller, a reman (15k miles) turbo, and just last week had to replace the PMD (relocated on the skidplate). I purchased it from the original owner, and the engine has never been rebuilt, or had head gaskets replaced.

Lately, the coolant temp has begun to rise and fall erratically. Today on the way home from work the temp went up and never fell, sat around 145-150 deg. I shut it off and let it cool, and it had apparently hydro-locked and would not crank. After further cooling, it finally cranked and immediately started billowing out white smoke, obvious head gasket failure.

Now, on a regular gas engine (what I'm familiar with) with 300,000+ miles, I would not consider trying to only replace head gaskets. I would be looking at a full rebuild. I know the longevity of these engines is outstanding, which brings me to my question...

Is just replacing head gaskets a good decision here? The engine consumes about 3 quarts of oil every 5k miles, but still runs (ran) great! 15mpg with the race car under tow. I really love the Sub, but rebuilding/replacing an entire engine is just not justifiable considering what the vehicle is worth.

Any and all input is welcome!

[Robyn]

First things first here.

WELCOME TO TDP :D

I would get the coolant out of the thing at least so you dont get any more into the cylinder.
Drain the crankcase of all the crap, refill and run for a short time but not long enough get it hot (no coolant ok)
Dump this stuff and refill with 50/50 oil and tranny fluid. run a couple minutes and drain again.

Leave dry.

Now get the heads off and see wasup in there.

My best guess is that you lost an end cylinder into the water jacket via the gasket seal ring around the cylinder.

#1,2,7,8 can do this as they border on a large passage at the ends.

This engine is very much like a mouse or a rat motor, just a V8

Here are a couple things to remember. The head bolts are a one time use item.

The push rods have one end (ball) marked with copper color and this goes up to the rockers. (very important)

Keep a map of where the injector lines go and keep them in pairs and remove them as such.

Cap your injector and pump HP fittings to keep crap out.

If the gaskets are the issue, make sure the deck and head surfaces are good and not erroded.

If ok clean well and install a new set of FELPRO head gaskets and new bolts.

These bolts are TTY (Torque to yield) the sequence and value is important.

First time to X then second time to Y then 1/4 turn more.

Very important to follow instructions with the bolts. Bolts come with a special orange sealer. Dont mess with it or add other stuff. This seals the threads.

You dont need to mess with the IP. The engine will go right back to work as though nothing has happened if you dont touch the IP.

Might want to replace the rocker guide buttons too.

Keep us posted

Robyn

[wstukas]

Thanks for the welcome! and the great info!

So if I find no pitting or cracks, do you think bringing a 300k mile engine back to life is a good idea?

[Robyn]

If the engine had good oil pressure the prospects are good that you can get a fair bit more miles from the old girl after fixing the head gaskets.

Hmmm Looking at your first post. IMHO rebuilding the engine would definately be worth it. With the cost of a new rig so high, you can drive every penny out of the beast.

Unless the body and interior are just a total roach I would yank the engine out and do a freshen up.

Rings, bearings, timing chain, set of lifters. either repair the heads or get a fresh set from a place like Clearwater cyl head in FL ($670 set delivered)

For a very small amount of money you could have the engine in very good condition and then probably get the rig another 150K or more down the road.

A set of gaskets and such up top will get it going for sure but at 300K I would be asking some questions myself.

I did an overhaul on our 94 Burb at 237K (head gasket went away)

The rig has 267K now and its a semi daily driver.

We paid $8K for the truck back in 04 and the head gasket went in spring of 05
Ripped the engine out the day after it got sick and (April 29) and had it all back going again (July 4th)

Your call though but by my judgement the old girl could easily tow your racer for several more good years.

best

Robyn

[Squatch]

My 94 suburban blew a head gasket at 202k and i put reman heads and new gaskets on only to have the crank go out 1000 miles later. If you are taking it to a shop the man hours involved with swapping the heads are within an hour or two of swapping the engine. The money I spent on parts and labor was essentially flushed when the crank broke so I was kicking myself for not springing for the longblock the first time. If nothing else it is piece of mind. The guys at Heath diesel recommended the Diesel Depot in Sandersville, GA. They put a balanced 6.2/6.5 conversion engine in for me and I have almost 20k miles on it with no issues. Hope this helps, good luck!