I posted this over in forced F/I and Forced Induction as well:

Friend of mine has as the title says, build #11 from Calloway. Car has very low miles (I believe less than 20K) and he is thinking about selling it for a new Grand Sport or possibly getting his problem fixed and keeping it.

His problem is overheating when it is in slow traffic and it is hot outside with the a/c running. I had the same problem with my c5 and went with a Dewitts radiator and it fixed the problem. I asked him about the radiator and he states it is an aluminum radiator (w/o paint) so it sounds like an aftermarket item. I also asked about fans (I don't know if the c4's had fans on them) and he "doesn't know".

I asked him if he knew what thermostat is in the car and he does not
know (he is the second owner and has had this car for years).

He said the main reason of selling the car is that it is so uncomfortable to drive in the summer which is all the driving the car has ever got. He lives in Utah and I believe he bought the car in Denver years ago so the car has been in high altitude all of its life. I asked him if the car has ever been tuned and he replied no.

Being an twin-turbo setup any of you guys have any ideas?

Thanks

 

Start with the basics and work up from there. Id start the car and let it get to operating temp then wait for the fans to come on. If they dont ever come on it could be a fuse or a relay. If they come on and it still over heats Id test the thermostat or buy a new one. That should get you started.

 

Just wondering. I thought there was only 1 sledgehammer built. Maybe I'm wrong. That car was capable of 220 mph. I know your friend has a twin turbo. It's #11 of what and how many?

 

Perhaps it one of B2Ks ordered through the dealer.
1990 saw the lowest number of (B2K) Callaway Twin Turbo Corvettes ordered with 59 with only 58 actually built says Wikipedia.

 

Yes, its not the Sledgehammer but a b2k car.

The b2k comes with a stock radiator. Callaway does sell a big radiator for the b2k cars that will certainly cool it down. My 88 b2k would run hot in the summer when the AC was on.

Send your buddy to www.callawayownersgroup.com

 

Good points.


1990 had stock radiator. Good suggestions.

 

Flush the cooling system and then change the coolant and install new thermostat. As well, check for cooling fan operation as well. Also check for seeping out of the bottom of the water pump, indicating the water pump is going bad. Post some picts of the car, that's a rare C4.

 

Thanks but why would he refer to it as the "Sledgehammer". What is difference between the b2K and the hammer?

Thanks

 

About 480hp, 75mph, and $200,000...

Overheating isn't an uncommon problem on an older car. The radiator needs to be clear of debris and obstructions, and the fans need to turn on for it to stay cool when moving slow or stopped. It's not likely related to the turbos or anything like that, the engine isn't making 400hp when creeping along in traffic.

 

There was only one Sledgehammer, I know where it's located and have been to the owners garage to see it. Calling a b2k a "Sledgehammer" is a common misstatement. No biggie.

I'd love to see pictures of the car

 

He told me that there were 14 hammers made and his was #13. He must have been misinformed.

Thanks for the insight.

 

 

Pressure test the system and the radiator cap. As stated this is not a Callaway corvette specific issue. Check the cooling system like you would any other car.

 

I hope he finds the problem & does not overheat that rare engine causing damage to it.If he was near me I would come to him & find the problem for free as long as I got couple rides in it,in the spring.Like what was previously stated,start with the basics.Make sure theres prenty of coolant in the engine,overflow & tank.Check & clean debris in front of radiator & between radiator & condensor.Run engine up to 230 degrees to verify the cooling fans come on while having a running garden hose nearby to spray on radiator if cooling fans do not come on.Check for coolant leaks before you start & check while car is running.Even if its not a "Sledgehammer" its still a Calloway.Its a amazing vette & rare either way.When he gets it going,have him make a video & post it here or on Youtube.Only seen maybe 1 video of a C4 Calloway.That would be a very popular & interesting videoKeep us posted

 

He's not talking about the Callaway Speedster is he? There were 14 or so of those made. A racing buddy has one tucked away in his garage. It was the one used in the BF Goodrich ad way back then.

http://www.supercars.net/cars/372.html

 

No, the car in question is a 1990 Callaway Twin Turbo coupe. Was on ebay a few years ago with some parts from AZ Speed and Marine. Red over black coupe.

 

 

He did tell me he had it for sale on ebay at one time. I think either the highest bid was $34,000 or that is what is was asking for it (I can't remember).

I have never seen the car. I live in St. Louis and he lives outside of Salt Lake. We work for the same company and I have known him for years.

 

I saw the sledgehammer years ago in the corvette museum. i was dissapointed when i returned this year and the sweetheart wasnt there.