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I have a 1993 2500 4 wheel drive with a 6.5 turbo diesel pickup. My problem started with a complete loss of power 3 months ago. I took it to a reputable diesel mechanic and he rebuilt the injection pump. Truck worked great for 2 weeks. All of a sudden there was bubbling in the coolant tank. I can take the radiator cap off and it looks like a pot boiling. Took it back to the reputable diesel mechanic. The mechanic thought it was a blown head gasket. He took the heads off and inspected it and reassembled. Still bubbled. He got re-manufactured heads and replaced one and then the other. Still bubbled. He tried 2 new radiators, several new thermostats, replaced the water pump and fan clutch. Still bubbles. There is no water getting in the oil. Does anyone have any thoughts on where to go next? The mechanic is at a loss. I love this old truck and do not want to get rid of it. It has been well taken care of. HELP!!!!
 

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Welcome to DieselPlace

I moved your post over to "6.5L" for better views and responses to your issues
:thumb:
 

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I have a 1993 2500 4 wheel drive with a 6.5 turbo diesel pickup. My problem started with a complete loss of power 3 months ago. I took it to a reputable diesel mechanic and he rebuilt the injection pump. Truck worked great for 2 weeks. All of a sudden there was bubbling in the coolant tank. I can take the radiator cap off and it looks like a pot boiling. Took it back to the reputable diesel mechanic. The mechanic thought it was a blown head gasket. He took the heads off and inspected it and reassembled. Still bubbled. He got re-manufactured heads and replaced one and then the other. Still bubbled. He tried 2 new radiators, several new thermostats, replaced the water pump and fan clutch. Still bubbles. There is no water getting in the oil. Does anyone have any thoughts on where to go next? The mechanic is at a loss. I love this old truck and do not want to get rid of it. It has been well taken care of. HELP!!!!
It's pretty quick and easy to pull the coolant crossover off and see if you have a compression leak on either of your heads. Really, the only other place it could be is cracked block...

Put a coolant pressure tester on and see if your system holds pressure. If it doesn't hold pressure it might be forcing coolant into the chamber, then when you start it it'll pop out some White smoke
 

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Does 93 have a radiator with cap, or does the overflow have the radiator cap?

There's a split year when they went to the capless radiator, and I can't remember when that was, 93-95 sometime....anyways, back to business.

First step-does the top coolant hose get hard immediately after first start? Yes or no?

If yes, something is bad in motor, could be bad block, could be something else. Could even be a bad remanufactered head...

If no...we'll help you through.

If the radiator has the cap, remove it-might help to drain a little before hand. You want the level just above the heater inlet, which should be about an inch or two below the neck. Turn on the truck and observe the coolant, does it immediately start to bubble? Does it rise quickly? There is some expansion going to happen when you heat up the coolant, but not enough to overflow, provided there is at least an inch before testing.

If nothing try revving the motor, the coolant should stay at about same level, any significant rising or overflow indicates a radiator blockage.

Let's start with that for now.

Sent from my SM-S920L using Tapatalk
 

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*face-palm*
The cure-all to every 6.5 problem ever, rebuild the IP.

But yeah, try to do what 1967KaiserM715 suggested and then sctrailrider's advice since it requires more time.
 

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I kind of doubt your "Mechanic" knows much about 6.5s or other diesels. The first thing I would have done when a customer came to me and said there were bubbles in the over flow. Would be to verify the problem and look for a simple fix like a leak. If not simple. Then do a compression check. So I could ID the problem area. Then take parts off the affected cylinders & heads and do a through inspection for damage and cracks. Guessing about, without confirming the problem. Then just throwing parts at it and hoping for the best. Is not what I call a " reputable diesel mechanic ". However it does pad his wallet nicely at your expense. If you cant do the work yourself. I would find a better, honest mechanic.
 

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I have a 1993 2500 4 wheel drive with a 6.5 turbo diesel pickup. My problem started with a complete loss of power 3 months ago. I took it to a reputable diesel mechanic and he rebuilt the injection pump. Truck worked great for 2 weeks. All of a sudden there was bubbling in the coolant tank. I can take the radiator cap off and it looks like a pot boiling. Took it back to the reputable diesel mechanic. The mechanic thought it was a blown head gasket. He took the heads off and inspected it and reassembled. Still bubbled. He got re-manufactured heads and replaced one and then the other. Still bubbled. He tried 2 new radiators, several new thermostats, replaced the water pump and fan clutch. Still bubbles. There is no water getting in the oil. Does anyone have any thoughts on where to go next? The mechanic is at a loss. I love this old truck and do not want to get rid of it. It has been well taken care of. HELP!!!!
I kind of doubt your "Mechanic" knows much about 6.5s or other diesels. The first thing I would have done when a customer came to me and said there were bubbles in the over flow. Would be to verify the problem and look for a simple fix like a leak. If not simple. Then do a compression check. So I could ID the problem area. Then take parts off the affected cylinders & heads and do a through inspection for damage and cracks. Guessing about, without confirming the problem. Then just throwing parts at it and hoping for the best. Is not what I call a " reputable diesel mechanic ". However it does pad his wallet nicely at your expense. If you cant do the work yourself. I would find a better, honest mechanic.
notice, the truck originally had a complete loss of power, which led the mechanic to rebuild the IP...

the bubbles started later. the mechanic may not be at fault here, but continued issues revealed additional symptoms.

that's where we come in with diagnostic and ideas for trouble issues. :coolnana:
 

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I did not even mention the IP in my post. Somebody else did. It was an old mechanical IP. So the mechanic was most likely right on that point.
With obvious combustion gasses in the coolant ("bubbling like a pot of water"). A compression test should have been the first thing done. Before just throwing parts, as he seemed to be doing. it. A number of thermostats, radiators, fan clutch ect. Have nothing at all to do with combustion gasses entering the cooling system.
This could easily be confirmed by a compression check and or a chemical test for combustion gasses in the cooling system. A professional diesel mechanic should have a compression tester and coolant test kit on hand at his shop.. Repairs done should have been based on the results. Not guesses. Like " The mechanic thought it was a blown head gasket". A compression check would have shown which cylinders were affected. Then with customers OK. Engine disassembled and A through inspection done for bad gasket, Cracked head or block, etched or corroded deck.
If the compression passed specs. Then yes its time to look else where.
Seems to me with all the parts installed.. My theory of throwing parts & hoping for the best holds up.
I am just giving my opinion to the post as written. Perhaps there is more to the story and I may have ben a little harsh on the mechanic. But the OP. I am sure has paid a lot of money. Just to have a truck in the same condition and have the same problem, as it was when they brought it to the shop.
 

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In addition, throwing parts at problems may not resolve due to the other fact that parts quality is not that good this days.

So, by changing so many parts, who knows that the newly replaced part is actually good?
 
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