5KIDS1WIFE

Hey guys, new member here.

I have owned seven 91.5 to 1997 12 valve pickups over the years and just cannot go without one of these trucks.

Picked up a bone stock one owner 89 D250 w/124K original miles this week ($1200.00). Body is nice and paint decent. Never towed a 5th wheel and looks taken care of.

Original owner was told it had a bad cylinder. It runs, but emits white smoke, idles very rough, and has mega blowby out the breather and oil stick. Also makes a "weezing" noise. Does not knock. Cummins Northwest shop told owner it is likely a bad piston/cylinder.

Any ideas what is wrong? I plan to pull the head this Saturday. What are my chances that the bore is still good? Could a bad head gasket cause all of this blowby or am I going to be looking at a bad piston?

I have searched all of the cracked head and bad piston posts and am curious what you guys think the problem might be before I actually tear into it.

Thanks, Jim

dpuckett

I think I saw that truck on autotrader, and I would just sleeve the one cylinder and put a new piston in if needed, and go omn with life.

Blown head gasket can cause all kinds of strange noises and conditions. Pull the head and let us know what happens. The local Cummins shop could have just been looking for an easy $5-7K.

Daniel

jogl

No sense guessing, plan for bad, hope for good, cross fingers, drink sacrificial beer and pull the head.

JP.

5KIDS1WIFE

Hi Gents.

I got the head off today. No. 3 bore is going to need a new bore and new piston (I think it will clean up with a max bore and no sleve). No. 3 piston looks like it has a broken ring. Part of the top edge of the piston is broke (about 1/8 inch by 1 inch around the OD). Near as I can tell the head gasket may have been leaking between No. 2 and No. 3. Would that cause a broken ring/piston?

All of the other bores look great with the famous cross hatches still visible.

So now it is decision time. The body is very straight (no rust at all and very few dings) and it does have 124K miles with good tires, maintenance history, etc. Any of your guys know how much the following will cost?

a. Machine work to bore oversize.
b. New cummins oversize piston (cummins book says you can bore just one)
c. New head. (I would go with a new style head with smaller dia injectors to avoid the crack issue) since I have this much labor into the thing. I see Tristate has dressed heads for about 450.00. As good as I can do?
d. Head Gasket kit.
e. New or used OEM or aftermarket injectors for 91.5 to 93 7 mm head.
f. Rings and rod and main bearings (Are rings needed based on 5 very nice bores?).
g. Engine gasket kit.

If I don't fix it, what do you think this truck would bring in as-is condition on ebay or CL? I did get this off autotrade for 1200.00 so am not hurt too bad yet.

Thanks in advance for your information. It is great to pull from all the experience on this board. Jim

wannadiesel

I would keep the head, especially if you're going to sell it later. With only 124k on it there's no need for a head unless you have cracks between the valve seats and the injector bore. Clean it up good in that area with a wire brush and look at it with a magnifying glass. If it looks good, reuse it. Plenty on non intercooled trucks are running around with the original head on them.

Inspect the bearings, as long as they look good there is no reason to roll in new ones at this mileage. Keep the pistons and rings together and reuse them.

Even with my list you're looking at around $500. Machine work is expensive.

Your list will run close to $2k. Before I'd do your list I'd look for a used motor.