Need help, Viper overheats.

[Bo knows]

OK, supercharger is off again. Am putting in a different brand of thermostat. Crank pulley bolt is tight. Coolant looks clean. Did a pressure test on the cooling system. Pumped 17 lbs of pressure in the system, after sitting overnight its all gone, back to zero. No visible leaks. Pulled spark plugs, no signs of coolant on any of the plugs. Cranked engine over with plugs out, no coolant mist. Checked engine oil, no signs of coolant in oil. Anybody got any ideas ????? HELP !!!!

 

[speedracervr4]

You obviously have a leak. Did you look underneath at where the block meets the heads to see if you can see coolant stains? Timing chain cover gasket is a possibility, but I would think you would see coolant in the oil.

 

[Jmch]

Your pressure tester could have just had a bad seal which would slowly let the pressure down without an actual leak. Did the coolant level drop at all? If its not leaking on the ground and its not going into the engine or puddled on the top of the block somewhere then its not leaking... if it is leaking internal you may only notice the oil level rise without running it.. but it would have to be significant, coolant is heavier than oil, if you drain the oil watch for coolant to come out first. If its been run with coolant in the oil then its a noticeable oil consistency/color difference. Since you went 2 weeks with no issue after the install and have tried everything but, I would get the block tester to check for cylinder gasses present in the coolant. this would indicate a head gasket issue, you can have compression leak into your coolant instead of the usual coolant into the cylinder. This does cause the same issues you have by creating air pockets when running. I would guess head gasket since you have already tried everything else.. and you had two weeks of what I assume to be forced induction amusement

 

[speedracervr4]

I suggested the block tester three weeks ago (post #4)...

 

[Jmch]

I suggested the block tester three weeks ago (post #4)...

I know.. great minds think alike . I was reiterating with a brief explanation as to why since he hadn't mentioned trying it yet..

 

[Bo knows]

Have had the pressure tester on for 5 days, no leaks, no signs of coolant in the oil or oil in the coolant and no loss of coolant. I think JMCH might be right, the tester may be leaking down. I will test the coolant with the block tester but the engine has to be running to do it so I'm putting it back together with a different brand of thermostat. Thanks to everyone for all the input. I should have it running tonight. I will keep you posted.

 

[Bo knows]

Drove the car for the last three nights in a row. No overheating so far. The two things I did differently are changed from a NAPA thermostat to a Federated Auto parts thermostat. Also where the thermostat sleeve slides up and down in the thermostat housing it felt really tight in the seal, so I took a fine dremel and went around the seal until the thermostat sleeve slid up and down easily. Will drive it some more this weekend and keep you posted. Thanks to all for the input !

 

[Fast Viper Dan]

Could be a bad sending unit.
Dose your fan cycle normal? If you are in fact running hot, your fan will continue to run.
Sometimes things are simple??

 

[Bo knows]

I've been driving the car around for a week now and no overheating problems so I'm officially declaring it fixed! The only problem is I don't know what fixed it. Was it changing to a different brand of thermostat or slightly enlarging the thermostat seal ? Any thoughts ?