eap Posted March 20 Share Posted March 20 I've had my 87 comanche (2.5L, 4cyl, 4×4) for well over a decade. It's always run great and I've kept it maintained. About 5 years ago I started having a run issue in summer. I recently found out, after thousands of $ of unneeded repair, that it's heat soak. Is there a solution to heat soak or do I just leave it running so the coolant stays circulating? Link to comment Share on other sites More sharing options...
gogmorgo Posted March 20 Share Posted March 20 What components are heat soaking? And do you know for sure heat soak is the problem? Just wouldn’t want to recommend more unnecessary repairs. If it’s an issue with fuel rail/injectors there were heat shields for ‘97+ XJs, although I don’t know if they’ll work for Renix. The low-buck proof of concept solution would just be wrapping the affected components in aluminum foil. You might also find some level of success with an exhaust wrap or coating to help keep infrared radiation down in the engine bay directly under the fuel rail. Adding vents to the hood is also popular. Should we assume that thousands of dollars in “unnecessary” repairs means your cooling system is in perfect working order too? Link to comment Share on other sites More sharing options...
eap Posted March 20 Author Share Posted March 20 4 minutes ago, gogmorgo said: What components are heat soaking? And do you know for sure heat soak is the problem? Just wouldn’t want to recommend more unnecessary repairs. If it’s an issue with fuel rail/injectors there were heat shields for ‘97+ XJs, although I don’t know if they’ll work for Renix. The low-buck proof of concept solution would just be wrapping the affected components in aluminum foil. You might also find some level of success with an exhaust wrap or coating to help keep infrared radiation down in the engine bay directly under the fuel rail. Adding vents to the hood is also popular. Should we assume that thousands of dollars in “unnecessary” repairs means your cooling system is in perfect working order too? I'm told cooling system is fine, however this was told to me by my mechanic I've been taking my truck to for 4 years now for this issue.... I'm not a mechanic and while trying to do my own research so I can keep my truck, I came across this forum. Thought I could get some tips from people who are familiar w this truck. I need to know what to ask about when I take it to a new mechanic cuz it's not going back to the previous one. Link to comment Share on other sites More sharing options...
eap Posted March 21 Author Share Posted March 21 Mines 2.5L Link to comment Share on other sites More sharing options...
eaglescout526 Posted March 21 Share Posted March 21 Ok. What component(s) are getting heat soaked? What is this issue you’re having? When you say heat soak, it sounds pretty broad and vague. I’ve had mine for 8 years out here in AZ with no problems of heat soaking. If it’s a starting issue after shut down, your CPS or coil could be failing. 4.0L and 2.5L are very different from each other. 90% of everyone on here has the 4.0L. We’re the 5% that has the 2.5L. Link to comment Share on other sites More sharing options...
eap Posted March 21 Author Share Posted March 21 3 minutes ago, eaglescout526 said: Ok. What component(s) are getting heat soaked? What is this issue you’re having? When you say heat soak, it sounds pretty broad and vague. I’ve had mine for 8 years out here in AZ with no problems of heat soaking. If it’s a starting issue after shut down, your CPS or coil could be failing. 4.0L and 2.5L are very different from each other. 90% of everyone on here has the 4.0L. We’re the 5% that has the 2.5L. For at least 4 summers now I'll take the truck out, doesn't matter how far or long, and shut it off... When I go to start it again it doesn't want to start. And when it does it will quickly die out. I will have to throttle the gas to keep it going and it takes a long time to idle normal again w/o dying. If it sits overnight and the entire thing cools down it's fine. Link to comment Share on other sites More sharing options...
eap Posted March 21 Author Share Posted March 21 Just now, eap said: For at least 4 summers now I'll take the truck out, doesn't matter how far or long, and shut it off... When I go to start it again it doesn't want to start. And when it does it will quickly die out. I will have to throttle the gas to keep it going and it takes a long time to idle normal again w/o dying. If it sits overnight and the entire thing cools down it's fine. When trying to research this I found a YouTuber describe my exact problem w his comanche. That's why I'm thinking it's heat soak... I'm hear to learn so pls feel free to let me know what you think. Link to comment Share on other sites More sharing options...
pizzaman09 Posted March 21 Share Posted March 21 The photos are a bit close but you can see parts of the factory heat shield under the injectors in these photos of my 90 Renix 4.0L. Link to comment Share on other sites More sharing options...
eap Posted March 21 Author Share Posted March 21 2 minutes ago, pizzaman09 said: The photos are a bit close but you can see parts of the factory heat shield under the injectors in these photos of my 90 Renix 4.0L. I'm gonna go pop the hood real quick.... I don't remember seeing anything like this on mine, but that exhaust manifold bolt looks familiar 😅 Brb Link to comment Share on other sites More sharing options...
eaglescout526 Posted March 21 Share Posted March 21 3 minutes ago, pizzaman09 said: The photos are a bit close but you can see parts of the factory heat shield under the injectors in these photos of my 90 Renix 4.0L. Guys, he’s got the 2.5L. Heat shield won’t help since he’s got the TBI OP, I would look into testing your CPS when this happens. When it’s heat soaked, take a volt meter, have it set to AC, stick the probes into the connector for the CPS at the sensor, crank it over and see how many volts it generates when heat soaked. Chances are, that’s the issue. Link to comment Share on other sites More sharing options...
eaglescout526 Posted March 21 Share Posted March 21 Ok I hid some stuff. We’re confusing the OP. OP has the 2.5L and has a heat soak issue. No heat shield will fix this, lets look at electrical possibilities. Link to comment Share on other sites More sharing options...
eap Posted March 21 Author Share Posted March 21 7 minutes ago, eap said: I'm gonna go pop the hood real quick.... I don't remember seeing anything like this on mine, but that exhaust manifold bolt looks familiar 😅 Brb Trying to figure out how to post my photos... Gen x here and never learned computers bc we used to have real jobs lol. Too bad I didn't get into mechanics. Link to comment Share on other sites More sharing options...
eaglescout526 Posted March 21 Share Posted March 21 Just now, eap said: Trying to figure out how to post my photos... Gen x here and never learned computers bc we used to have real jobs lol. Too bad I didn't get into mechanics. When you open a new post box, there’s a paper clip and two options down at the bottom of the box. You can drag the files that you want to upload to that paper clip or hit the add files button and browse for your pics you want to upload. Link to comment Share on other sites More sharing options...
eap Posted March 21 Author Share Posted March 21 11 minutes ago, eaglescout526 said: Guys, he’s got the 2.5L. Heat shield won’t help since he’s got the TBI OP, I would look into testing your CPS when this happens. When it’s heat soaked, take a volt meter, have it set to AC, stick the probes into the connector for the CPS at the sensor, crank it over and see how many volts it generates when heat soaked. Chances are, that’s the issue. I'll take it in and have that checked when it acts up again... If nothing else pans out. Thank you. Link to comment Share on other sites More sharing options...
eap Posted March 21 Author Share Posted March 21 1 minute ago, eaglescout526 said: When you open a new post box, there’s a paper clip and two options down at the bottom of the box. You can drag the files that you want to upload to that paper clip or hit the add files button and browse for your pics you want to upload. Link to comment Share on other sites More sharing options...
eap Posted March 21 Author Share Posted March 21 Still trying. I might have to get a niece or nephew to help me. Link to comment Share on other sites More sharing options...
eaglescout526 Posted March 21 Share Posted March 21 17 minutes ago, eap said: I'll take it in and have that checked when it acts up again... If nothing else pans out. Thank you. You don’t have a volt meter? Most of us here don’t trust mechanics these days to know what they’re working with when it comes to these old Jeeps. They want plug n play and let the computer tell them what’s wrong. Chances are you’re gonna keep blowing money till you get an old timer who knows how to work on these and use a volt meter. I don’t mean(and not trying) to sound harsh, but from the sounds you have wasted enough money that the help of us can help you better than a mechanic can. The computers these Jeeps use are pretty easy to work with and all the sensors are based on voltage input, output and ground resistance to operate per the factory spec. I encourage you to get a volt meter and not waste anymore time at a mechanic. Link to comment Share on other sites More sharing options...
eap Posted March 21 Author Share Posted March 21 Just now, eaglescout526 said: You don’t have a volt meter? Most of us here don’t trust mechanics these days to know what they’re working with when it comes to these old Jeeps. They want plug n play and let the computer tell them what’s wrong. Chances are you’re gonna keep blowing money till you get an old timer who knows how to work on these and use a volt meter. I don’t mean(and not trying) to sound harsh, but from the sounds you have wasted enough money that the help of us can help you better than a mechanic can. The computers these Jeeps use are pretty easy to work with and all the sensors are based on voltage input, output and ground resistance to operate per the factory spec. I encourage you to get a volt meter and not waste anymore time at a mechanic. I agree but I don't know anyone... People I used to associate w were toxic, disfunctional and addicts.... Had to cut ties. I worked in fire fighting and trails, some construction, never learned computers n don't have social media. Yeah mechanics are grifters for sure. If I could afford tools I would get them , but I live on disability. Anything I can save or work under the table at the expense of my health goes to trying to get my truck fixed. I don't even know how I would find a knowledgeable old timer in my area. Craigslist is sleezy so that's a hard pass. I'm in nor cal... Bit north of Sacramento. If you know anyone in the area let me know. Thanx eagle scout 😎 I'll keep gleaning info from this forum so if I go to a mechanic at least I'll have the right questions and hopefully more knowledge. Link to comment Share on other sites More sharing options...
eaglescout526 Posted March 21 Share Posted March 21 1 minute ago, eap said: I'm in nor cal... Bit north of Sacramento. Theres quite a few members on here in cali. Anyone here able to lend him a hand? If youre gonna take it to a mechanic again, get two books, The Jeep Comanche Factory Service Manual and the AMC|Jeep Throttle Body Injection Service Manual and have them read and study how to work on your truck. 4 minutes ago, eap said: If I could afford tools I would get them A Volt meter would be all you need in this situation. This way if we can diagnose its the CPS, you could order one, have a shop then swap it in. Link to comment Share on other sites More sharing options...
eap Posted March 21 Author Share Posted March 21 6 minutes ago, eaglescout526 said: Theres quite a few members on here in cali. Anyone here able to lend him a hand? If youre gonna take it to a mechanic again, get two books, The Jeep Comanche Factory Service Manual and the AMC|Jeep Throttle Body Injection Service Manual and have them read and study how to work on your truck. A Volt meter would be all you need in this situation. This way if we can diagnose its the CPS, you could order one, have a shop then swap it in. I got a neighbor might have one. Thnx again. Link to comment Share on other sites More sharing options...
eap Posted March 21 Author Share Posted March 21 Just now, eap said: I got a neighbor might have one. Thnx again. Someone told me about them manuals a while back I'll have to see about getting them. Link to comment Share on other sites More sharing options...
eaglescout526 Posted March 21 Share Posted March 21 Of course and no problem! Link to comment Share on other sites More sharing options...
cruiser54 Posted March 21 Share Posted March 21 Wanna try something that you can do yourself and needs to be done as a matter of course anyway? Something your average mechanic is NEVER gonna do? Spend an hour or less with basic hand tools. Go to www.cruiser54.com and COMPLETE Tips 1,3, and 5. Do this before anything else. Link to comment Share on other sites More sharing options...
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