Cracked radiator after thermostat change

[tyler711]

Last weekend, I replaced the 180* thermostat that's been in the jeep with a 195, and while I was at it I replaced the 20 year old factory rad cap since the gaskets were looking tired. No leaks, temps look great now, but today I got home and found my radiator had cracked (under the belt routing sticker, so it took a bit to find).

I had actually been second guessing replacing the rad cap because I figured if the old one was less effective, it might not be putting the full 18 pounds in the system and I was worried a new one might blow a hose or the radiator. Could that be what happened, or could the hotter temp have caused it?

Obviously I'm on to replace the radiator next, but want to make sure I'm not overlooking something else I should consider or take care of as I do so. Is there anything else I should test or review as I replace the radiator?

2006 TJ 4.0 auto

 

[Chris]

Last weekend, I replaced the 180* thermostat that's been in the jeep with a 195, and while I was at it I replaced the 20 year old factory rad cap since the gaskets were looking tired. No leaks, temps look great now, but today I got home and found my radiator had cracked (under the belt routing sticker, so it took a bit to find).

I had actually been second guessing replacing the rad cap because I figured if the old one was less effective, it might not be putting the full 18 pounds in the system and I was worried a new one might blow a hose or the radiator. Could that be what happened, or could the hotter temp have caused it?

Obviously I'm on to replace the radiator next, but want to make sure I'm not overlooking something else I should consider or take care of as I do so. Is there anything else I should test or review as I replace the radiator?

2006 TJ 4.0 auto

It is possible that replacing the old cap with a new, properly functioning one increased the pressure in the system. If the radiator was already weak or had any pre-existing fatigue, the extra pressure could have caused it to crack.

The higher temperature from the new thermostat can contribute to stress on an already aging radiator. If it was close to its limits, running at a higher temp could push it over the edge.

Take a good look at the hoses and the water pump. I'd make sure they are in good condition and not showing signs of wear. It might be wise to replace any old hoses while you’re at it.

I'd also consider flushing the cooling system while you're replacing the radiator.

It sounds like you’re on the right track with replacing the radiator. I know you mentioned your radiator cap was 20 years old. If the radiator is the same age, then it is to be expected that it cracked. 20 years for a radiator is a long time. That would be a testament to how well the factory Mopar radiators were made. Just make sure everything else in the cooling system is in good shape to avoid further headaches in the future.

 

[John Cooper]

Last weekend, I replaced the 180* thermostat that's been in the jeep with a 195, and while I was at it I replaced the 20 year old factory rad cap since the gaskets were looking tired. No leaks, temps look great now, but today I got home and found my radiator had cracked (under the belt routing sticker, so it took a bit to find).

I had actually been second guessing replacing the rad cap because I figured if the old one was less effective, it might not be putting the full 18 pounds in the system and I was worried a new one might blow a hose or the radiator. Could that be what happened, or could the hotter temp have caused it?

Obviously I'm on to replace the radiator next, but want to make sure I'm not overlooking something else I should consider or take care of as I do so. Is there anything else I should test or review as I replace the radiator?

2006 TJ 4.0 auto

Im in the minority here, but my 06 TJR split the top tank and I had mine replaced by a trusted Radiator shop.

I also bought a spare radiator as a back up too.

Factory with the new top tank is still going strong.

 

[tyler711]

Thanks guys. Looks like there is plenty of reading here on this site for radiator options, so I'll start my homework there.

I did do a full radiator flush the weekend before... I had another thread about that here since karma gave me a transmission CEL for all the hours of TLC the Jeep got with that process .

 

[Harold&Cat]

This thread has an example of what a 21 year old radiator is capable of .

https://wranglertjforum.com/threads/radiator-exploded.85438/

 

[tyler711]

Geeze, looks like I got off easy then. I had to lift up the belt routing label to see it.

 

[Harold&Cat]

Geeze, looks like I got off easy then. I had to lift up the belt routing label to see it.

View attachment 652127

I am very thankful that yours did not come apart like mine while you were looking for the leak . I've decided that in the future , I'll let the vehicle set a little while before looking .

 

[Obi-Wan]

Geeze, looks like I got off easy then. I had to lift up the belt routing label to see it.

 

[Zorba]

If'n you don't know when the last time the water pump was changed, change it.

 

[tyler711]

When I bought it, the water pump was dripping. I had too much going on at the time so I had a shop do the pump. They did the pump, replaced the thermostat but put in a 180*, replaced my factory constant pressure clamps with worm gear clamps, and the parts bill listed green coolant for the top-off. I didn't know enough at the time, but my recent cooling system overhaul has mostly been undoing their work.

 

[Link]

When I bought my Jeep, I was checking everything and found the radiator cap wasn't holding pressure. It was the winter so not a big deal. I replaced it with a new radiator cap and took it for a drive. The radiator split. I'm sure the radiator had been on its last legs for a long time but with no pressure, it stayed intact. However, once I put a new radiator cap on it, it was too much and blew. No doubt it would have blown much sooner if it had a properly working radiator cap. Put a new Denso radiator in it and it's been great.