I was hoping to get a little more input before I face the inevitable.


History: 2001, I bought a 1990 F-450 Flatbed tow truck. 7.3 IDI. True mileage unknown but I thought maybe 200,000 as it already had a reman engine.


2003 - installed a Banks Turbo. Shortly thereafter basically blew the engine. Had a new reman installed by the local IH dealer, who re-installed the Banks.


In the last 10 years, I put about 20k miles on it, so it sits a bit. .About a year + ago, it developed excessive coolant pressure and I quit driving it. It was also blowing a bit more dirty exhaust. I don't think it was whitish. Bottom line, now I need to fix it.


I am NOT a diesel mechanic, nor have I done much more than replace the waterpump, fan clutch and injector pump. I have done a lot of work on other areas of it.


Preliminarily, yesterday I pressurized the cooling system to 13+ psi and pulled the relatively new glow plugs. No change in pressure or sounds of air or evidence of water escaping as I did it.. They all look good with no signs of damage.


Last night I pumped it up to 20+ psi. I cranked the engine a bit just to see if I could uncover any potential holes in a cylinder. 16 hours later I checked it and it was only down to 10.


From what Ive read, it seems like my problem(s) could be a bad head gasket(s), cracked head(s)/ or block....or cavitation. None of that makes me happy on a reman engine I've only put 20k miles on and done routine maintenance. It was $8k to have it done in 2003, and I won't pay that again.


I'd like to narrow it down. Seems funny that if I pressurize the system, and I cant "reverse" the symptoms and hear anything coming out the glow plug holes.


My thinking....next,
1) drain oil and look for water.
2) Get test strips to check oil for exhaust contaminants EDIT....ooops, check coolant, not oil.
3) pressurize each cylinder via the glow plug holes and wait for air bubbles to appear in the radiator from the offending cylinder. Guess i'll need to turn the engine for that one.


I imagine there is just no other "problem" that could cause the same issue. I wondered if there might be some leakage via the water pump or some other area into the cooling system. ...just hopeful thinking before I get the "pull the heads or engine" notice.

 

What do you mean by exessive pressure? The rad cap is the pressure regulator, so it can only build so much. Do you have any other symptoms?

 

It overcomes the radiator cap, and fills the overflow.
I've tried replacing the radiator cap ( I think it's a 17#)
to no avail.


I'm going back out in a bit and drain the oil. I've just started checking the compression after hunting all afternoon for the correct fittings to use my gauge.

 

It is supposed to overcome the cap and push fluid into the overflow. Then when it cools off it sucks it back in the rad. So far you havent given any symptom of anything abnormal.

 

Normally a system only does that when it overheats. This starts pumping coolant out before it reaches normal operating temperature.


Let's put it this way, if I let it run, it would evacuate the entire cooling system.

 

It should slowly build pressure as it warms up. A blown head gasket could be pumping air into.the system. You could remove.the cap and see if it is getting a lot of air bubbles. You could also pressurize each cylinder with air.

 

^^Pull the radiator cap and start the engine, watch into the radiator and see if you see any bubbles float by. You can also buy a litmus test kit that will tell you if you have any exhaust getting into the coolant.

 

In the middle of my original post, I acknowledge that it could be 1 of 3 possible major issues. One of those is a blown head gasket. A diesel being no different than a gas engine in that regard, as far as I can tell, those symptoms would exist in either of the three suspected problems. Blown head gasket, cracked head or cavitation would all cause contaminants in the cooling system. I'd like to be able to narrow it down before I tear it apart so I can focus on a particular cylinder or component.


If one or more are more "usual" then I would focus or steer my initial tests in a particular direction. I know I need to do more tests, but I thought since there are diesel dudes on this site, it might be a good place to ask. I've had a lot of SBFs, but my experience on diesels is limited.

 

Compressed air in cylinder through glow plug hole to find which cylinder. Check at tdc and bdc. If it only leaks at bdc it is cavitated. Otherwise hg or cracked head.
Cavitation is rare.

 

Thanks, I'll give that a shot tomorrow.

 

All the engines I've had pushed coolant out into the overflow as they get warm -- there's a reason there is a ''cold max" and "hot max" line on that container...

 

Yes, mine too. This is NOT normal.

 

Just out of curiosity, if it is head gaskets, maby it's just a loose bolt; you're only seemingly getting leakage when the engine is running and producing high pressures.
Perhaps checking/re-torquing the headbolts might be worth a shot?

 

I know I'm late to this thread, but any resolution?

 

Yes!
I pulled the glow plugs and ran compression tests. One was a bit low.
Also ran compressed air into cylinders.
Pulled the heads and a local shop cleaned, inspected and didn't find any cracks. They resurfaced them (VERY minor) as he didn't like the way the pre-combustion chamber mated.
Deck surfaces were good.
No oil in water nor vice-versa.
I'm suspecting there was a leak in the head gasket around the passages blocked by the expansion plugs as there was rust around them. Who knows. Nothing obvious to my eyes on the head gaskets.


Installed ARP head studs
New Victor Reinz gaskets
So far everything feels good.


Bought the Ferret stuff to set IDP timing and I think it's good-to-go.


Now I need to decide if I keep or sell the rollback it's in.