I think I have a worn out 6.9...
 

Well fellas I finally got around to doing the compression test on my truck. It's an 84 F250 with the 6.9 mostly stock N/A. Here's the numbers... #1 390 #2 355 #3 375 #4 375 #5 420 #6 380 #7 380 #8 425. I wasn't particularly happy about what I found, but such is life. The weird thing is, it still seems to run pretty good and carries good oil pressure. It never had a ton of power, but IDIs are known for that. Anyway I guess the only question I have is. How worn out is this engine? How much longer can I expect it to live? Any feedback is appreciated, thanks again!

Never perform tests like this on a thing u like and are happy with, u always find something that will not make u happy. Couple questions: The test was performed on cold or hot engine? Besides the rings it could be the valves. If it starts cold I would not worry, depends what u do with it.

I did the test on a cold engine, it hadn't been ran in a couple days. I had a feeling I might find this to be the situation. It has been using excessive amounts of oil for the 7 years I've had this engine in the truck. It doesn't seem to have gotten any worse than it was back then. Other than the usual IDI traits of cold starts, it doesn't start too badly. I used to use this truck as a full time tow rig and plow truck, always served me well. I recently bought a cherry 97 F250 PSD, which has taken over most all towing duties. I can't bring myself to part with the old girl , we still use her as a plow truck/farm truck and as a secondary back up vehicle.

International never stated an actual number for compression. IIRC it is said that all cylinders should be within 10% of each other.
With that being said the only one that would worry me is #2, but even then its not all that low. Plus, as said above it could be a valve problem. But as a plow/farm truck I think that it would last for quite sometime.

Run that sucker! If it starts cold, it's got plenty of compression to do the job. If it's low on power(especially due to ring leakage), a turbo will help(find a used kit for cheap).
These engines don't die too easily. They just drink oil.

I've been beating the crap out of this thing for years. Nothing seems to phase it. I do have a Banks Sidewinder I've had full intentions of installing on it. I held back from doing it because of the excessive oil consumption. Before I installed this engine (came from an 87 F250) I did a complete gasket job and switched over to the ARP headstuds. I've always blamed the oil issue on valves, but still wanted a compression test to be sure. I'm thinking I'll leave it be and keep running it. I'm currently doing the e-pump conversion, hopefully that will help the hard starting issues I've been dealing with. Thanks for the feedback!

If itnwere me, id watch craigslist and try to find a running spare engine for $5-600, then put the turbo on my current engine.

I thought about doing something like that too. I considered finding a rebuildable core and going through it from the ground up. Set it up with lower compression pistons, upgraded camshaft, some head work, etc. Set it up for lots of boost. Then the billfold comes into the picture, probably not the most economical decision. At least not at the moment, I will probably keep my eyes open for another engine anyway. I don't drive it every day, so it doesn't have to be perfect; just reliable.

Put the turbo on it. The oil use probably won't get much worse, and it'll feel a lot more fun to drive.


As far as rebuilds go, I ended up with a 'stock' rebuild by a local shop. I'm not sure decompression is needed for good HP... but I would talk to Justin about a set of powerstroke-modified rods if you want to go over 350-400HP, as that's the weak point here.

Wow, from the sounds of it I really have nothing to fear in dumping some boost to the ol girl! Like I said it still runs pretty good, apparently these engines will take more pounding and abuse than I realized. I show it no mercy, running WOT most of the time. I've always felt the IDIs never really got the respect they deserve. I'm not overly concerned about making crazy power numbers with this truck, would be fun though. I say this because I recently purchased a cherry 97 sc lb F250 4x2 with the PSD/E4OD. This truck will take over a majority of the heavy long distance towing duties. I wanted something a little newer with more creature comforts and obviously power. The biggest downfall to my 84, is it's a regular cab basic truck, 3 speed, 4.10s. It rides like a brick, geared low, just not a nice truck on the highway. Plus the wife has a bad back, she can't stand riding in it. I have a soft spot for the old girl, I've had it for 8 years now. The thought of getting rid of it saddens me. Besides it's long ago paid for and it's dirt cheap to insure. Not to mention the cool factor of passing vehicles 10-20 years newer broke down on the side of the road.

Compression test won't tell you where the pressure is going. Run a leak down test if you have an air compressor. At most it will cost is a set of valve cover gaskets. Yank the valve covers, loosen the rockers so the valves are closed, remove the glow plugs and put air into the cylinder with a rubber tipped nozzle. Valves will be air out of the intake or exhaust, rings will be out through the crankcase. If it's the valves, that's the perfect excuse for some lapping, ARP head studs and a turbo...

Still need to do this on my own. I have a smokestack coming out of the dipstick tube, but starts and runs great, and hauls ass for a NA engine.:-jammin

Last night I discovered the mystery oil leak. Upon removing the mechanical fuel pump, I discovered the mounting bolts were backing out. Yeah, that will probably be the next step I take if I decide to turbo it. No smoking out the dipstick tube, probably valves in my case. I have another set of heads I could go through...