Hi,

I have a 1988 Ford F350 7.3 Diesel.

It is a service truck we use at my tire store. Several weeks ago we began to have a white smoke issue followed by what appeared to be hydrolock. When we checked it there was coolant in the oil and a little oil in the coolant. My mechanics (we are primarily an undercar shop) suggested we remove the heads and check for head gasket problems. While he was starting on the truck I researched the problem on this website. Several good posts discussed the cavation issue and I relayed the information to my mechanic. He checked the left rear cylinder for holes at it' s low point as best he could since the engine was already disassembled. He says he didn't find any holes. We replaced the head gasket (felpro), had the heads worked, and used new bolts. The truck ran much better. Two weeks later it won't crank. Figured the starter had been damaged from initial hydrolocks. We replaced the starter. Wouldn't crank a few days later so we checked for hydrolock We removed the left side glow plugs turned the engine over and coolant came out the LR hole. What do I do?

I have used this site several times for other issues relating to this truck. I want to say thanks for that help and anyone that responds to my post

Scott

 

Welcome to the FTE IDI forum

Sounds like you may have a cavitation problem all right. Unless you blew a head gasket or cracked a head somehow. The part about it running much better for a couple of weeks kinda points to something other than cavitation. How much better is "better"?

Can't see how replacing the head gaskets and bolts wouldn't make the problem any better at all - even for a couple of weeks. Unless it had BOTH cavitation problems AND a blown head gasket.....

 

The man who drives the truck said the truck started much quicker and had more power after we replaced the headgasket. We were forced to drive the truck yesterday after we relieved the hydrolock and he says it still runs better now than before except for the hydrolock

The heads were magnafluxed.

I should have said that the truck has 58,000 original miles on it. (thought this might reduce the possiblity of cavitation.

I think what you are saying makes sense. Should I tear that side down and check the new gasket?

 

Is it pressurizing the cooling system - devloping high pressure in the radiator?

 

i am really not sure. I don't think it is excessive now. We will crank the truck and check and see. Maybe I can check it with a pressure gauge.

 

No it does not appear to be building excessive pressure in the radiator.

 

There are five ways for coolant to get into the cylinder.
Cavitation - to check for this fill the radiator completely full of water and apply air to the glow plug hole and allow the piston to rotate to BDC. If the cooolant raises in the radiator neck or you have bubbles you have found the problem cylinder. Repeat for all cylinders. CAUTION WHEN YOU APPLY AIR PRESSURE THE MOTOR WILL ROTATE TILL THAT CYLINDER IS AT BDC

Blown head gasket - check the same way as checking for cavitation - when installing new head gaskets the block deck and head must be clean, dry and oil free. I wipe mine down with acetone or laquer thinner before I install the gasket and head. Assembly oil on the head bolts must be used very sparingly or it will contaminate the gasket.

Leaking valley pan gasket - although the intake is a dry intake with no coolant in it, the valley pan gasket does block off several coolant passages in the head that are close to the intake port. A leaking valley pan gasket where the leak is on the head side of the gasket can let coolant into the intake port. Was the intake torqued down properly? I also clean these parts with acetone prior to install and then spray them with copper gasket material, but I am running a turbo.

Cracked head - look for cracks near the water passages and between the valves.

Cracked block - look for cracks from the coolant passages to the cylinder on all cylinders.

 

thank you Dave!

We will make these checks tomorrow.

Scott

 

There is some really good info over on another IDI site. This site won't allow cross linking to it. But the info is at oil burners

It's in the 6.9/7.3 forums FAQ

 

I have read that some porosity is sometimes only detectable during a hot pressure check. the holes come from the ping of the diesel combustion separating nitrogen gas out of the liquid and slamming the cylinder into the bubble(drills holes). proper levels of nitrates in the coolant prevent this and I must have those levels checked at every oilchange in my 96 Mack. reputable builders sleeve every cylinder on a 7.3 to std. to guarrantee no porosity which is hard to detect. 6.9's (are supposed to)have thicker walls

 

How do I apply air to the glow plug hole? can I just use my air chuck that has a rubber tip and press it against the glow plug hole, or do I need to use a threaded adapter of some type. If I need a threaded adapter, where could I buy one?