1992 F-250 4x4, 5sp manual, a/c, rebuilt 7.3 diesel w/banks turbo: Driving home from work I noticed my heater did not work (temp gauge riding). Temp was indicating higher than normal by the time I arrived home where I then observed coolant overflowing from my "overflow" tank. Top of radiator was cold, bottom was hot. Figured it must be the thermostat. Just replaced the thermostat (figured out the old one opens at 200 degrees rather than 195 it's rated at, but it opens) and when I started it up, it pumped cold coolant out into the overflow tank immediately. Radiator cap is a 7psi cap and the engine/radiator and all associated rigging has about 25,000 mile on it. Ideas??
I've done a few searches and don't find anything that gives me a hint as to where to go from here. I assume the water pump is okay because it pumps the coolant out to the overflow tank

 

Okay, I just poured hot water back through the top radiator hose, got the thermostat to open, vented some trapped air and then topped the radiator off. When I cranked the engine, it stopped for a second then cranked and started. I had the radiator cap off and it blew water all over the place until I got the engine shut down (about 3-4 seconds). So, is this a head gasket problem?

 

If the top of the rad was cold and no heat came from the heater after engine warm up , it is possible the pump did not have enough coolant to prime after the thermostate change and the heat from the engine caused the pressure to vent the coolant out the overflow. But if after engine warm up the heater was warm check the thermostat to see if its faulty. Test all thermostats in the house in a pot even new ones . Good luck, keep it simple!

 

sounds like the pump was not primed fill again with hot water put cap on start and check for heat as engine warms

 

check for heat using the in cab heater

 

sounds like you either have a bad head gasket or cavatated block.the crank-stop-crank-blow coolant out the radiator cap hints of a hydrolicing, then pressuring the coolant system when the engine fires.

 

check your engine oil for whiteish color (water in oil)

 

Unfortunatley that's kind of the conclusion I've come to. I have looked at the oil on the dipstick and nothing, though there was some condensation on the inside of the oil filler cap.

 

I second the head gasket. Classic symptoms.

 

Thread moved to the proper forum.

 

Remove the glow plugs.
Crank the engine over.
Look for the glow plug hole the coolant blows out of.
A blown head gasket can put coolant in the cylinders.
The coolant does not compress which is hydrolocking the engine.
However the coolant will leak through the ring gaps and then the engine will turn over and start.

Caution Warning #1
I cracked a block from improper sleeve installation in a reman engine.
This caused the head gasket to blow.
The compression leaking into the cooling system built 30 PSI in the cooling system in 15 seconds after starting.
This cost me a new heater core and radiator.

Caution Warning #2
When you crank the engine with the glow plugs removed do not look under the hood or have anyone close to the engine compartment. The coolant will come out the glow plug hole under several hundred pounds of pressure.

After you stop cranking the engine there will be enough evidence around the glow plug hole to see which cylinder the coolant is in.
Then you know which head has to come off to figure out the damage.

Something to think about.
The pressure in the cooling system will make the water go into the cylinder faster when you shut the engine off.
Cavitation can occur at any point up or down the cylinder wall.
If it is cavitated near the bottom the water may just run into the oil pan if the cylinder stops with the rings above the hole. The engine will crank and start normally, no water will blow out the glow plug hole.
However if the piston stops with the rings below the hole, when you go to start it and that piston is on the compression stroke, when the water on top of the piston reaches the head it stops right now. If another cylinder has fired before that happens rods can be bent and pistons can be broken. In extreme cases the crankshaft may also be damaged or broken.

Another classic symptom is white smoke or vapor coming out the exhaust while running. This will smell very sweet usually with most antifreezes.

 

Thanks for the help guys. It's headed for the shop tomorrow

 

I wish you luck, hope for a head gasket.

 

Thanks, me too. I'll post the results.......zed

 

We are having a similar problem with our 93 7.3. Husband noticed truck overheating and unfortuanately the radiator seems to have popped a vessel! But there is oil inside the radiator. Now we are jumping around among the scenarios and are afraid we are looking at a new engine. We have been told that the engine oil cooler and go out and push oil into the radiator. We've never noticed an antifreeze smell with the exhaust and I really can't figure how we'd miss something like that. Obviously the other scenarios are the head gasket and then the cracked block. There is NO evidence of oil on the dipstick, but we have not yet had the time (make that nerve) to loosen the oil pan plug and see what comes out first. It's been sitting now for two weeks - had to buy a Ranger off a friend so he could get back to work out of town. Any update from Zed or thoughts from anyone else are appreciated - I can't stand the thought of $6000+ repair bill...