Would a bad radiator cap cause the reservoir tank in the front bumper to overflow?

[AAKVIPER]

The radiator cap looks to be from original 1994 circa..But After driving 20 miles to a cookout each way, I came home parked the Viper and the next day I had the coolant all over the floor. I pulled the bumper off the Viper and found the reservoir tank full to the top and looks like coolant overflowed.
No coolant leak anywhere else and the car is not running hot and the temp gage is normal. . The thermostat is working fine and no over heating. No oil and coolant mix on the dipstick. 8,500 original on the Speedo.

I drove the Viper all summer and no problems with the coolant. So I remember reading that a weak radiator cap can cause the coolant to purge all the way to reservoir bottle behind the bumper. Anyway any ideas from members.? Can a weak radiator cap cause this mess by just being to old to hold pressure? Or could this be a burping problem or air pockets?
Thank you in advance, Arthur

 

[JonB]

Re: Would a bad radiator cap cause the reservoir tank in the front bumper to overflow

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Unlikley but possible

What is 95% more likley is AIR IN THE MOTOR. Search BURPING YOUR VIPER, or call a trusted vendor here for advice: Tator, DCPerf. Roe, PartsRack.....any one of em has done this for over 15 years

 

[bluesrt]

Re: Would a bad radiator cap cause the reservoir tank in the front bumper to overflow

if you had air in the motor, it would overheat, i would check for hydrocarbons in the cooling system, does the car have a good heater?

 

[Mopar Steve]

Re: Would a bad radiator cap cause the reservoir tank in the front bumper to overflow

I think both of these answers are correct, but combine to give you a whole picture. The air in the system will displace water causing the system to overheat. When it overheats the water expands to the overflow tank. When it cools it is supposed to draw that water back into the SEALED system. When the cap is bad there is no longer a sealed system and air will get in and create all kinds of issues.

Important now is to burp the cooling system, be sure that all the containers are correctly filled, be sure your mix is correct, and get a new cap. Since Partsrack chimed in with an answer, I cant think of a better place to spend your money. Reward those that help and contribute to your hobby.

 

[cfiiman]

Re: Would a bad radiator cap cause the reservoir tank in the front bumper to overflow

Yes, I've had 2 go bad and my latest problem is a bad thermo which I am planning to do this fall.

 

[AAKVIPER]

Update

Update, I put a new radiator cap yesterday from Dodge $11.00. I did the burping procedure and now the Viper is fixed..

The old cap was not holding any pressure (4 LBS) tops, I drove the
RT- 10 for another 30 miles for good measure and parked the car overnight, checked this morning the over flow tank, and perfect level.

Who would have thought a radiator cap could cause all this coolant mess. One positive byproduct was, the Viper runs cooler, about ten degrees on average from where it used to be on the temp gage. I should have done this fix last season.

Forum members you know your Viper stuff.

Thanks for all the help. The moral of my hardship was read this forum for help and do not run a 14 year old plus radiator cap.

Arthur

 

[Steve-Indy]

Re: Would a bad radiator cap cause the reservoir tank in the front bumper to overflow

I have had/found several bad "radiator" caps through the years. Hopefully, you are good to go now...BUT, don't be too surprised if you overflow again after several full drive cycles. This can be due to a leak in the hose found coming off of the neck of the pressure bottle's cap ("radiator" cap)...so that fluid pumps over during coolant expansion due to heating, but the leak causes loss of vacuum normally created upon cooling, thus an overflow can ultimately occur AGAIN. This can be fixed with a small hose clamp at each end of this very short hose...start with the end by the cap.

SUGGESTION: After you have serviced the coolant, ALWAYS log the amount of coolant in your pressure bottle AND the overflow bottle (in the nose) BEFORE you start the engine (cold) and after you are finished driving (fully warmed). Do this for 5-10 full drive cycles and you will detect any "pathologic" fluid shifts EARLY...BEFORE they bite you !!