Overheating

[ComancheDude11]

Howdy, i've got an 87 4.0 renix Comanche. It has the idiot lights and the temp light is usually on really dim or not at all. After driving it for about 20 minutes it starts spewing coolant out of the plastic jugg on the passenger side. I know it's a pressurized system from the info on here but it doesn't seem to pressurize. There is no crack on the jugg, but the lid won't tighten up. It is filled up halfway when cool. So is there a replacement lid?

[87MJTIM]

Mine blew its top on a hot summer day. I ended up purchasing new bottle and cap. I only used the cap, though. No problems since.

[cruiser54]

Go to Napa and get a new cap part number 703-1396.

Start there.

[ComancheDude11]

Well it never did this when it was 100+ degree weather, it has started now that it's around 90-95 dergree weather.

[ParadiseMJ]

Well it never did this when it was 100+ degree weather, it has started now that it's around 90-95 dergree weather.

 

Ambient temperature aside, it's doing it now because your cap can't hold pressure, and now has air in the system. 10 degrees outside doesn't mean squat to a 200+ degree engine. It's all about the pressure.

[ComancheDude11]

I don't think my cap could ever hold pressure, it would not get tight but it now has a hose clamp around it so it does get tight and hold pressure.

[cruiser54]

Well then, don't listen to us and keep fighting the problem by yourself. For $8, I'd sure give it a try. Just because the clamp is holding the threads doesn't mean the cap is good at holding pressure.

 

How can it be spewing out coolant like stated in your first post and still hold pressure? Makes no sense at all.

[pilecenturyfarm]

mine was spewing like crazy and turned out my thermostat was stuck... replaced it and no worries now. oh and listen to the guys on here... they have some good advice.

 

[ComancheDude11]

I replaced the thermostat yesterday. We now think that the coolant isn't flowing.

[Exgrayxj]

I don't think my cap could ever hold pressure, it would not get tight but it now has a hose clamp around it so it does get tight and hold pressure.

 

I am in agreement with you, my xjv8 .cap would not hold enough on the threads of the neck to maintain pressure, I did the same as you, hose clamp. Replacement tank so it would be perty.

I think that problem was caused by an aftermarket tank, I got a new cap from NAPA, then from Jeep, and still had that problem.

I have now gone to a aluminum radiator and done away with the remote pressure tank (well, it is there still, but now being used as overflow tank, so there is no pressure).

My opinion is that the aftermarket (and we all know where THOSE come from)tank has slightly undersized threads.

As of a couple days ago that damn tank is back in service though, on the mj. Crummy 22 year old tank split.

I already have noticed the cap seems to not tighten...and I thought aging it would make it better. :wall:

[cruiser54]

I don't think my cap could ever hold pressure, it would not get tight but it now has a hose clamp around it so it does get tight and hold pressure.

 

I am in agreement with you, my xjv8 .cap would not hold enough on the threads of the neck to maintain pressure, I did the same as you, hose clamp. Replacement tank so it would be perty.

I think that problem was caused by an aftermarket tank, I got a new cap from NAPA, then from Jeep, and still had that problem.

I have now gone to a aluminum radiator and done away with the remote pressure tank (well, it is there still, but now being used as overflow tank, so there is no pressure).

My opinion is that the aftermarket (and we all know where THOSE come from)tank has slightly undersized threads.

As of a couple days ago that damn tank is back in service though, on the mj. Crummy 22 year old tank split.

I already have noticed the cap seems to not tighten...and I thought aging it would make it better. :wall:

 

That's EXACTLY why you use the Napa 703-1396 cap. To solve that problem!!!

[Exgrayxj]

[quote name=

I got a new cap from NAPA' date=' then from Jeep,

 

 

That's EXACTLY why you use the Napa 703-1396 cap. To solve that problem!!![/quote]

 

Miss something? :huh???:

[cruiser54]

[quote name=

I got a new cap from NAPA' date=' then from Jeep,

 

 

That's EXACTLY why you use the Napa 703-1396 cap. To solve that problem!!![/quote]

 

Miss something? :huh???:

 

I missed NOTHING. The 703-1396 cap is from a Volvo. It fits better, holds the threads tighter (even on a crappy bottle), and has a higher relief pressure.

[Exgrayxj]

AHA! Thank you for including THAT part of the information, I will pick one up tomorrow!

:waving:

[HOrnbrod]

I can never understand why people stay with the antiquated closed cooling system and don't convert it unless you're a masocist. There's nothing good about it, endless pressure bottle and cap problems, can't burp the things, nothing buy one problem after another. :yes:

 

[cruiser54]

I'm thinking sometimes it's all they can afford to do at the time.

 

But thanks for the turd polish photo!!!

[HOrnbrod]

Perhaps. But I've seen guys buy billet aluminum pressure bottles for $100+ trying to make these systems reliable. I'm sure you have too. You can convert for that.

[cruiser54]

Perhaps. But I've seen guys buy billet aluminum pressure bottles for $100+ trying to make these systems reliable. I'm sure you have too. You can convert for that.

 

That's certainly a tipping point.