Cooling system cavitation in '91 2500HD 5.7/Auto.

[03s10cc]

This question is for a good friend of mine who doesn't use the computer much (if at all).

 

He has a 1991 2500HD with a 5.7 backed by an auto. trans. The truck's cooling system is having a cavitation problem that he's having a hard time determining the cause of. He has been a professional mechanic for quite some time, specializing in automotive HVAC systems for many years. That said, I'd think that he's gone through the basics such as correct coolant to water ratio and coolant type, etc... but any info. would be a help.

 

Regards,

 

Russ

2003 S10 4WD Crew Cab

[mmmikkke]

How does this cavitation problem manifest itself? Erratic readings on the temperature gage? If so, has he checked the sending unit?

[Haulin' 8.1]

Serpintine water pumps are designed to turn backwards. If you mix the wrong type for the belt drive they will captivate.

 

Vernon

[03s10cc]

I just spoke to him a little while ago...

 

The cavitation manifests itself as an audible gurgling/sloshing sound from the cooling system. He hasn't had to add coolant. The water pump was replaced. He verified that the impeller was the same as the old one. He's tried to purge the system a couple times now with no luck. The restrictor is still in place. He's tried purging both with and without the restrictor in place. Thanks so much.

 

Regards,

 

Russ

 

This question is for a good friend of mine who doesn't use the computer much (if at all).

 

He has a 1991 2500HD with a 5.7 backed by an auto. trans.  The truck's cooling system is having a cavitation problem that he's having a hard time determining the cause of.  He has been a professional mechanic for quite some time, specializing in automotive HVAC systems for many years.  That said, I'd think that he's gone through the basics such as correct coolant to water ratio and coolant type, etc... but any info. would be a help.

 

Regards,

 

Russ

2003 S10 4WD Crew Cab

 

<{POST_SNAPBACK}>

 

 

[wht2500hd...]

could be a head gasket where gases are entering the cooling system, or a crack.

 

Jack up the front end as high as possible, remove radiator cap and run engine to purge air.

 

you can also drill a small pin hole in the thermostat. make sure t-stat bypass is not clogged.

 

never heard of a 1991 HD ...

[kdog55]

I was going to add what wht2500hd said. My wifes car had the same problem and we found out the hard way it was a blown head gasket at the waterjacket-to-cylinder area. No water in the oil at all, but when the piston would pressurize the cylinder, it would push the gasses into the waterjacket at the blown headgasket area. Then when that pocket of air would get to the waterpump, well obviously it would lose prime and then eventually overheat. I hope his problem is not this, but it is something to check.

This problem was on an Olds Cutlass with the infamous Quad-four engine that the aluminum heads were famous for warping and I think the early versions of the 5.7 were notorius for the same thing.