4.0l XJ Overheating

[bruggz351]

Gday Rastus, originally, I removed my bash plate when the XJ was first purchased, simply because it was in the way.

ATM, I'm not really having overheat problems. Just hot.
I have been running a cooler thermostat, 180*F, which over the past 18 months to 2 years has been quite good but, this summer I've noticed the temp creeping up a little more than normal.
Camp Coffs was a breaze in October. A LOT of high revs in low range hill climbs. No temp probs what so ever.
The 'heat wave' days and hot humid days late December and during January were the testers.
Long hill climbs at 60klm/h would see the temp spike to 115 @ the head and 100 - 105 @ the top hose. Normal running is 85 - 90 and 80 respectively.
I'm only taking notice now because it hasn't been hot for quite some time.

First change, I will re install the front bash plate and take note of the running temps.
Another idea I have for bonnet vents is like the old 68 Plymouth Roadrunner, dual side ways scoops. As close to the sides as possible though. I don't want to upset the pressures at the rear of the engine bay. I still want the air flow down past the trans. Hopefully the side scoops won't effect that.
I think I'm also going back to a 195*F thermostat, to keep temps stable. I don't like keeping temps right on the cusp, but I dislike erratic temps more.

Patients will be a virtue with this considering the way I function, and I shall pray Murphy farks the hell off and leaves me to my devices..

cheers

[rastus2571]

Originally Posted by bruggz351

Gday Rastus, originally, I removed my bash plate when the XJ was first purchased, simply because it was in the way.

ATM, I'm not really having overheat problems. Just hot.
I have been running a cooler thermostat, 180*F, which over the past 18 months to 2 years has been quite good but, this summer I've noticed the temp creeping up a little more than normal.
Camp Coffs was a breaze in October. A LOT of high revs in low range hill climbs. No temp probs what so ever.
The 'heat wave' days and hot humid days late December and during January were the testers.
Long hill climbs at 60klm/h would see the temp spike to 115 @ the head and 100 - 105 @ the top hose. Normal running is 85 - 90 and 80 respectively.
I'm only taking notice now because it hasn't been hot for quite some time.

First change, I will re install the front bash plate and take note of the running temps.
Another idea I have for bonnet vents is like the old 68 Plymouth Roadrunner, dual side ways scoops. As close to the sides as possible though. I don't want to upset the pressures at the rear of the engine bay. I still want the air flow down past the trans. Hopefully the side scoops won't effect that.
I think I'm also going back to a 195*F thermostat, to keep temps stable. I don't like keeping temps right on the cusp, but I dislike erratic temps more.

Patients will be a virtue with this considering the way I function, and I shall pray Murphy farks the hell off and leaves me to my devices..

cheers

I've only done to mine what we have all done to ours on here. I see a lot of merit in what Peter said though. I'm always open to trying new things and he sure as hell makes a lot of sense. He is not a jeep owner though. I may or may not try what he said about the vents. I hardly have time to be able to sleep, eat, etc before I.go count white lines again. Let alone go chopping my guards or bonnet. Lifes great...Living the dream.

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[junglejuice]

Originally Posted by rastus2571

I've only done to mine what we have all done to ours on here. I see a lot of merit in what Peter said though. I'm always open to trying new things and he sure as hell makes a lot of sense. He is not a jeep owner though. I may or may not try what he said about the vents. I hardly have time to be able to sleep, eat, etc before I.go count white lines again. Let alone go chopping my guards or bonnet. Lifes great...Living the dream.

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I have some spare bonnets if you wanna experiment with venting....

[rastus2571]

Originally Posted by junglejuice

I have some spare bonnets if you wanna experiment with venting....

I'll see how I go when I get myself settled into my own place. I'm just not keen on the idea of drilling big holes in my inner guards. I think it would obviously weaken the body and could cause cracking. I saw on jimmys buildup a great set of bonnet vents. I'm going to pm him and find out where he got them.

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[94xjeep]

Last of the XJ's are 14 years old now and one that worked for me was removing the water pump, thermostat housing, and all the steel welsh plugs off the side of the engine block under the exhaust manifold. manifold off to do this job. pressure wash out all the rust, scale and muddy crude from around the lower area of the engine block. Run the genuine thermostat, gen water pump gen 16 psi cap. These are partial pressure caps, you tube will explain it to you. Chrysler has used this system for 50 years now. CPC and tridon caps are crap the valve at the bottom of the radiator is spring loaded, it's not meant to be on jeep. Replaced all coolant hoses and I haven't looked back. take your time to clean out the block use wire to dig around for any lose material. due to the low flow of coolant around the cylinders this stuff builds up and up taking away the cooling systems coolant capacity. If you boil, this stuff comes lose and turns up in your radiator tanks and jeep being cross flow type radiator this is not good at all as gravity works against you with cross flow radiators. When engine is off the whole lower tubes get this mud that sits in the tank(hot side) down the bottom. It runs into the tubes but due to the length of the tubes gravity makes it settle and form layers of mud rust ect. Now the lower part of the radiator is now slowly blocking off. Keep the reverse flushing up to date every 12 to 18 months and the radiator should keep going longer. Tip the radiator upside down and make a 90 degree nozzle that can spray high pressure water into the tank (hot side or inlet) through the radiator hose opening and watch the rubbish come out. for the tubes well you cant see them to see if they are blocked. but if you get mud from the bottom of the tank then I bet the tubes next to the mud are blocked. ADRAD radiator with dimple tubes works the best but I hate the material quality as I have had 2 of there radiators and they come apart at the tank header plate. they solder it up and it does the same thing again and again. Due to the cost of copper they are mixing other crap material in to the copper to make it stretch out and the copper is contaminated and solder wont stick. Don't get me started on copper radiators

[Rodgebone]

94xjeep

Last of the XJ's are 14 years old now and one that worked for me was removing the water pump, thermostat housing, and all the steel welsh plugs off the side of the engine block under the exhaust manifold. manifold off to do this job. pressure wash out all the rust, scale and muddy crude from around the lower area of the engine block. Run the genuine thermostat, gen water pump gen 16 psi cap. These are partial pressure caps, you tube will explain it to you. Chrysler has used this system for 50 years now. CPC and tridon caps are crap the valve at the bottom of the radiator is spring loaded, it's not meant to be on jeep. Replaced all coolant hoses and I haven't looked back. take your time to clean out the block use wire to dig around for any lose material. due to the low flow of coolant around the cylinders this stuff builds up and up taking away the cooling systems coolant capacity. If you boil, this stuff comes lose and turns up in your radiator tanks and jeep being cross flow type radiator this is not good at all as gravity works against you with cross flow radiators. When engine is off the whole lower tubes get this mud that sits in the tank(hot side) down the bottom. It runs into the tubes but due to the length of the tubes gravity makes it settle and form layers of mud rust ect. Now the lower part of the radiator is now slowly blocking off. Keep the reverse flushing up to date every 12 to 18 months and the radiator should keep going longer. Tip the radiator upside down and make a 90 degree nozzle that can spray high pressure water into the tank (hot side or inlet) through the radiator hose opening and watch the rubbish come out

excellent info mate! it's an extreme measure but this underscores the serious need to flush the system regularly!!! its one of the most neglected maintenance procedures for the XJ but #1 on the list of failures.

[rastus2571]

That's it. Flush the hell out of it.

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