Hey guys, I'm new to the forum since i bought an old diesel ford. It needs quite a lot of work but i'm excited to work on it and figure out diesel since i haven't actually worked on them before. I have worked on a couple engine rebuilds before so I should be able to handle whatever gets thrown at me. A guy not too far from me decided to get rid of his 85 f250 4x4 and i picked it up. I haven't seen it run but my cousin drove into my driveway so it does work but it is getting oil in the coolant system. I suspect maybe a blown head gasket. what could be an easy way to test for a blown head gasket? it also didnt start for me the first time i tried to start it but i suspect maybe the battery is too dead. I am planning to asking many questions to help figure it out but look forward to fixing it.

 

Welcome to the site. If you have oil in your coolant the seals on your oil cooler might be bad. The best way to diagnose this is to do a hot compression test with all of the GPs removed. If you have a blown head gasket the compression test will ID it. If the compression is good then R/R the oil cooler and install new seals.

 

I appreciate the answer. With the hot compression test, do I need the engine warmed up before testing? And what are the compression numbers that I should be getting? I asked the old owner of the truck how to get it to start and found there is a little button to turn on some kind of ignition to cold start it. I'll definitely look into the oil cooler since I really don't want to pull the engine. I was thinking of still pulling it though and maybe replacing some gaskets since the whole engine looks all greasy. I think it might be leaking oil somewhere as well.

 

The IDIs leak oil from the back of the head gaskets when they get loose. I wouldn't worry about removing the engine to re-gasket it unless you're leaking oil profusely. FWIW, my truck burns/leaks 1/4 quart every 100 miles or so. I've read about engines that leak alot more AND alot less. It's just the nature of diesel engines.

When you do the compression test make sure the engine is up to operating temp. Then get your work gloves on and remove all the GPs for the test. HF has a kit that works with our engines:

https://www.harborfreight.com/diesel...set-63726.html

Unless you're going to spend big bucks on a SnapOn or OTC compression gauge just get a cheapie. I did all sorts of reading before buying a Lang compression tester on Amazon and it ended up breaking after testing 3 cylinders. I finished the job with one from HF.

Here's a good thread on compression test numbers:

https://www.ford-trucks.com/forums/9...a-7-3-idi.html

When I did my compression test I got 355 psi +/- < 5%. I did the test cold with the GPs in the engine. It wasn't until later that I read that it should be done hot without the GPs. Like a compression test on a gasoline engine your looking for oddball numbers that aren't similar to the others.

Also, you can R/R the oil cooler without lifting the engine. This was the first maintenance I did on my truck and you can get the oil cooler out, it's just a messy job!

You mentioned you have to push a button before starting the engine. This is a manual GP relay. I switched my truck to manual GPs because the GP controller is a POS. One of our IDIs should only take 4-6 seconds of GPs to start unless it's bitterly cold. Most will probably say less time than that but my engine and IP are old and worn. Just make sure you don't use 10+ seconds of GP time or a tone of ether. An NEVER use ether and GPs together.

 

Glad to have you on board,
Where are you at?
You should put your truck details in your signature line so it will always show up with your posts, it makes it easier for members to help you,

the worst part of these old trucks is trying to figure out what the previous owner "modified" to make it run better, prepare to put on you sleuthing hat as you just found out with your "little button" to cold start it,

Don't assume anything while you trouble shoot problems,

The FAQ section at the top of the page has lots of great tips, especially about the glow plugs and you should be able to find a good write up about the oil cooler fix with pictures,

.

 

I would love to add a signature but if I read correctly, I need to make some posts before I can add a signature.
With that said, it is a 1985 Ford f250 4x4 6.9l n/a. the wiring in cab looks kind of horrendous and the engine bay looks like a mess but the truck runs since i got it running today with just a little bit of starting fluid. The old owner told me the block is cracked but i had my doubts so i thought I'd take chance to ****** it since the truck was free. I noticed today when moving the truck that it looks like it was leaking what looks like water on passenger side on the block right next to the starter. I will upload some pics to show what i found but unfortunately it does looked like it is cracked.




i think the first thing I should do is figure out where this water is coming from and if its fixable.
Sorry about the bad pictures.

 

 

I would love to add a signature but i need to make 5 posts before i can.
I picked this truck up for free and it looked very clean. The wiring in the cab looks like a mess and the it definitely needs to be cleaned under the hood but it runs. The last owner told me the block was cracked but i had my doubts. after i started it up with just a little bit of starting fluid i noticed a leak from under that looks like water. i am really hoping that it isn't a crack in the block.

 

 

Oil in coolant is 99% a bad oil cooler o-ring, gasket, or cooler itself. When reinstalling the o-rings, make sure not to cut them. here's a video on the process: 6.9 and 7.3 IDI Oil Cooler Repair ? IDI Online


Water dripping down on the starter area could be a cracked block or HG, but it might just be a simple cracked heater hose going from the head to the heater core. Check the easy stuff first before investing in compression testers or other specialty tools. Might also be a bad seal on the t-stat housing. Or a coolant plug leak, either in the block or the head.

 

that leak is most likely the block heater that is in the freeze out plug hole above the starter.
as for compression test, anything over 350 PSI i call good, and i call over 400 damn good.
i also agree with the guys that it very well could most likely be a bad oil cooler before a bad head gasket.
that truck is clean enough to repair even if you have to drop another engine in it.

 

Thanks for the info guys. Tomorrow when I have a chance I'll remove the starter and get a closer look into what it could be. I will also look into replacing the o-rings for the oil cooler. I appreciate the help guys!

 

don't be afraid to ask questions. even if you think they are stupid.
the only stupid question is the one you do not ask.
we were all newbies at one time or another, and most of us learned the hard way because there were not any old farts to ask about these engines back when they were new.

 

X2. Always ask first. The veterans on this forum have made all the mistakes ourselves, so you don't have to.

 

Just would like to say welcome to the site.