Coolant loss (3 gallons) No visible leaks

Mekanik · August 15, 2007

I'm working on a 1990 e350 with a 7.3l idi. I'm not sure how many miles because the customer says that the odometer stopped working a few years ago. They say that there is at least 200,000 miles on the truck.

The customer's complaint is that they go through 3 gallons of coolant at a time. It runs pretty good and the customer says that there is no noticable white smoke from the exaust. I can't see any coolant leaks. The engine is pretty much covered in the usual diesel oil seepage.

A few weeks ago, I got this truck with the same complaint. I pressure tested the truck overnight and found a leaking upper radiator hose and found oil in the cooling system. I replaced the oil cooler, radiator hoses and the water pump because it was questionable. They have the same problem. I talked the driver. He says that the engine will start to overheat. He checks the coolant level at the radiator and adds a couple gallons of water. Yeah, they've been putting water in this thing. He drove it aprox 50 miles and checked it agian and it was 1 gallon low. He says that his partner was driving behind him this time and smelled coolant. The oil level is full and is not milky. Right now I filled the cooling system and put dye in it too. Any help would be greatly apriceated.

Keith Browning · August 16, 2007

With that age and mileage one cant help but consider corrosion of the base engine parts including a head gasket and even cavitation erosion! /forums/images/%%GRAEMLIN_URL%%/shocked.gif Thats a term we don't discuss much.

Alex Bruene · August 16, 2007

It's funny how you should mention cavitation erosion. I was at Cat school last week, and it turns out the instructor was a Ford tech. in the 80's and early 90's, and when teaching the cooling system portion of the course, he couldn't seem to get off the topic of how bad 7.3 IDIs were for cavitation. And who says cooling system maintenance isn't important?

Mekanik · August 16, 2007

If cavitation was the problem, wouldn't I see coolant in the oil? It looks like regular diesel oil.

LARRY BRUDZYNSKI · August 16, 2007

Sometimes you will sometimes you won't. On wet sleeve engines the cavitation happens to the cylinder liners and is just small pin holes that leak small amounts of coolant into the cylinders. I haven't seen a lot of cavitation on the 7.3's but usually we do drop in's before it gets that far.

Alex Bruene · August 16, 2007

If cavitation was the problem, wouldn't I see coolant in the oil? It looks like regular diesel oil.

The way it was put to me is that cavatation erosion normally (if not always) happens on the major thrust side of the cylinder. If it is only small pinholes, the pressure from the piston skirt will force oil through the small holes into the water jackets, but the cooling system pressure is not high enough to push coolant through the other way.

Mekanik · August 16, 2007

Originally Posted By: Mekanik

If cavitation was the problem, wouldn't I see coolant in the oil? It looks like regular diesel oil.

The way it was put to me is that cavatation erosion normally (if not always) happens on the major thrust side of the cylinder. If it is only small pinholes, the pressure from the piston skirt will force oil through the small holes into the water jackets, but the cooling system pressure is not high enough to push coolant through the other way.

So, if cavitation was my problem I would have oil in the coolant but, it would not be losing coolant. Right?

Mekanik · August 16, 2007

Well, here is the update. I have coolant in #8 cyl. I'm suspecting a cracked cyl head. Putting a head on this truck makes me very nervous because nobody really knows how many miles are on it. We are getting a used engine for this truck. Thanks for the replies. /forums/images/%%GRAEMLIN_URL%%/drinkingdude.gif

LARRY BRUDZYNSKI · August 16, 2007

Is there a possibility it could be a injector cup?

dieseltech · August 16, 2007

With the high mileage 7.3 that I delt with that had coolant lose but no signs of leaks almost always the problem cylinder was on the right side. After removing the pistons I would fine small pin holes/cavitation on the outside or coolant side of the cylinder

Mekanik · August 16, 2007

Is there a possibility it could be a injector cup?

Injector cup on a idi?

Alex Bruene · August 17, 2007

Originally Posted By: AlexBruene

Originally Posted By: Mekanik

If cavitation was the problem, wouldn't I see coolant in the oil? It looks like regular diesel oil.

The way it was put to me is that cavatation erosion normally (if not always) happens on the major thrust side of the cylinder. If it is only small pinholes, the pressure from the piston skirt will force oil through the small holes into the water jackets, but the cooling system pressure is not high enough to push coolant through the other way.

So, if cavitation was my problem I would have oil in the coolant but, it would not be losing coolant. Right?

I suppose it all depends on if the cavatation is high in the cylinder, or closer to the bottom, below the piston ring travel. I have only seen what cavatation looks like on an engine with a removable liner, not on a 7.3, but I imagine that if it were higher up in the cylinder, coolant could be consumed.

LARRY BRUDZYNSKI · August 17, 2007

Injector cup on a idi?

Sorry wasn't thinking...

WGLR13MWZ · August 17, 2007

Quote:

Well, here is the update. I have coolant in #8 cyl. I'm suspecting a cracked cyl head. Putting a head on this truck makes me very nervous because nobody really knows how many miles are on it. We are getting a used engine for this truck. Thanks for the replies.

Out of curiosity. What factors other than not knowing the mileage on that engine made your dealership lean towards a used engine? If that was the sole reason I also assume that you have maintenance records for the used engine you are putting in the vehicle? Why would you not sell a 6006,6V006, 6007, or 6V007 engine for this vehicle?

Mekanik · November 16, 2007

Sorry it took so long to answer your question. This dealer seems to like using used engines in vehicles. Its wierd isn't it. A while ago our dealer would sell an aftermarket extended service plan that would usally find a used engine, manual trans, transfer case instead of a new one or having us just fix it. I once put a used axle assy. in a truck and after it was almost all together, I pulled the diff cover to change the fluid. Suprise, the "new" axle was in worse shape that the one I took out.