donald.wade3 Posted August 4, 2019 Share Posted August 4, 2019 Back story. Bought 89 Comanche a year ago it drove fine then started to rev high after running for a while then putting in park and then on restart after a few minutes of being off. Wasn’t a daily driver so not too concerned with it at the time. Working to fix an oil leak, and replacing the RMS and OPG, then still had a leak. Moving to VCG, it isn’t a Renix cover. Checked the cast numbers on the head and it’s an 96-99, then checked the stamp on the block and narrowed it down to a 96. So someone had done a swap at some point. With that they kept the Renix intake and exhaust as well as the closed cooling system. Probably a few other things I’m not aware of yet. So my questions are can I just replace the intake and exhaust manifolds and convert to open cooling. I also want to add the sensors for oil pressure and temp as they are the sending units and lights. But keep the lights too. What else can I do as far as keeping it reliable and parts are readily available while keeping the 4.0. End goal- daily driver and overland rig Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
jdog Posted August 5, 2019 Share Posted August 5, 2019 Yes you can convert to open cooling system, I'm not sure on the manifold parts, I know someone installed a h. O. Exhaust onto a renix system. If you want both the lights and the gauge, you will have to install aftermarket gauge, not hard to do and readily available. 1988 swb 4.0 ax15 np 231 red with gray interior. Link to comment Share on other sites More sharing options...
Pete M Posted August 5, 2019 Share Posted August 5, 2019 what exhaust manifold do you have now? pics? Link to comment Share on other sites More sharing options...
donald.wade3 Posted August 5, 2019 Author Share Posted August 5, 2019 I have bought the aftermarket gauges just have to figure out the sensors and locations. It’s on the to do list for sure. I will get pics of the exhaust and intake manifolds tonight when I get home from work. I plan on doing the 97+ cooling system for sure and a few other things. Main goal right now is to figure out what I have and what I can do to get it back on the road. Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
donald.wade3 Posted August 10, 2019 Author Share Posted August 10, 2019 Sorry it took so long to reply. Got busy with life. Work and kids starting back to school and everything else going on. Here are pics from the underside. On the intake and exhaust side.Again I have been able to determine it’s a 96 4.0 HO with Renix intake and exhaust. Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
Pete M Posted August 10, 2019 Share Posted August 10, 2019 converting tot he open system is straight forward. should be a thread about it in the link in my sig. what is the reason for changing the intake/exhaust? Link to comment Share on other sites More sharing options...
donald.wade3 Posted August 11, 2019 Author Share Posted August 11, 2019 what is the reason for changing the intake/exhaust? No real reason. Trying to figure out a previous owners puzzle. I don’t know much about these 4.0l motors, as I’ve just started learning about them I have a 96 4.0HO and a Renix Intake and manifold. As far as I know the upgrade from the Renix is the head anyways. Once the intake is changed over, I would imagine, would changed the wiring and harness. Just trying to figure out my options to get this Comanche back on the road and reliable. Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
Pete M Posted August 11, 2019 Share Posted August 11, 2019 how many miles on the truck? It really appears that the previous owner blew the engine somehow and swapped in what he could find. these trucks are like legos. Link to comment Share on other sites More sharing options...
donald.wade3 Posted August 11, 2019 Author Share Posted August 11, 2019 how many miles on the truck? It really appears that the previous owner blew the engine somehow and swapped in what he could find. these trucks are like legos. There are 273+k miles on the Odometer. No telling actual miles on motor. Who knows what a previous owner has done. I contacted the guy that had it last and he claims he had no idea there was a motor swap. Even after claiming to own it for 4 years prior to me buying it. Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
Pete M Posted August 11, 2019 Share Posted August 11, 2019 Even though it's a late model engine, the HO generally refers to the 91+ Chrysler operating system. Personally I would treat it as a renix and leave it alone except for some minor upgrades. high idle could be a vacuum leak or a sensor going bad. there should be some sensor diagnostics in the link in my sig. also in that link is Cruiser's MJ tips. do all of them that apply. it addresses most all the shortcomings and age-related issues with our old Jeeps. Link to comment Share on other sites More sharing options...
donald.wade3 Posted August 11, 2019 Author Share Posted August 11, 2019 That’s what I'm thinking. I'm going to go through cruiser list and do a coolant system swap. I’m assuming the biggest upgrade was the HO heads. With the ports being bigger and less restrictive. My biggest thing is having the oil pressure and temp reading accurate. Which is why I’m switching to sensors and running separate gauges. I plan on, from the advice of a buddy, running an unlit propane bottle over vacuum lines to find out general area for high idle issue. Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
Pete M Posted August 11, 2019 Share Posted August 11, 2019 check your intake manifold bolts for proper torque. they have been known to become a bit loose and allow a leak. Link to comment Share on other sites More sharing options...
JustEmptyEveryPocket Posted August 11, 2019 Share Posted August 11, 2019 What gauges do you have on your instrument cluster? You can swap in one that has oil pressure and temp on it without having to run abunch of wires or crazy things. Link to comment Share on other sites More sharing options...
jdog Posted August 11, 2019 Share Posted August 11, 2019 I would look into cruisers tip 11, 14 21 and look into injectors for high idle, with my jeep it would idle high when it was first started and times after driving it for a while. I found that some one adjust the stop screw as a idle screw, also iac was dirty, after cleaning and adjusting it is doing better. as for the intake and exhaust, if its working fine now why screw with it? Link to comment Share on other sites More sharing options...
DirtyComanche Posted August 11, 2019 Share Posted August 11, 2019 I'd be torn on doing the intake/exhaust swap. There is more power to be made by doing it, that's absolutely for sure, but there is an awful lot of headache involved. I would solidly say it isn't worth it unless you're interested in trying to get as much power as you can, and damn the time and costs to do so. If you were to, you could either keep the Renix FI, or switch it to HO. Switching it to the HO would be far easier done with the XJ that engine came out of, assuming it was out of one, as you need all the wiring for the engine and cab (have to adapt some of it to work in the MJ), the ECM, etc, along with the intake/exhaust manifolds and associated bits, exhaust downpipe, etc. You can also just put the HO intake and exhaust on it and use the Renix FI, my Renix XJ is like this. You'll have to adapt the TPS, fuel lines, vacuum harness, intake, etc. I did it because I bought a stainless steel HO header to replace my cracked manifold, and when it didn't fit with the Renix intake I convinced myself that I should swap the intake rather than just buying a manifold/header that actually fit. In retrospect it was stupid and I wasted a ton of time on it. However when I pop the engine I have a HO head sitting here, so I will be able to get another 4 horsepower out of it next time. I'd guess your current high idle issue is related to the TPS or IAC, assuming the throttle isn't sticking. Link to comment Share on other sites More sharing options...
donald.wade3 Posted August 11, 2019 Author Share Posted August 11, 2019 If I can keep the Renix intake and exhaust I will do that. I do have plans on going through cruisers list and try to improve on the setup. The end goal is to have something reliable and easily maintainable. I try to do all the work myself. The current cluster is the one with the dummy lights. I have bought the 3 gauge kit with temp, oil pressure and volts. I don’t mind wiring them up and hooking them up. Kinda ocd with the wiring and everything in a loom and clean looking. I have my work cut out on this one. But I have a t-stat housing off of a 99 4.0 that has the sensor port. For when I do the conversion. I know the oil sending unit will have to be “T”ed off for both. I was looking last night at the head for the sending unit for the coolant light but couldn’t find anything. Which is probably why the PO hard wired the e fan to come on when the key is on. Tied in to the fuel pump too. Then then the hot wire into the fuse block for constant acc power. Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
Ωhm Posted August 11, 2019 Share Posted August 11, 2019 36 minutes ago, donald.wade3 said: The end goal is to have something reliable and easily maintainable. I try to do all the work myself. RENIX Engine Monitor (REM) Link to comment Share on other sites More sharing options...
donald.wade3 Posted August 11, 2019 Author Share Posted August 11, 2019 RENIX Engine Monitor (REM) I have seen these and tried to figure them out. I would imagine it’s like a scan tool in monitor mode. I would like to invest in one for sure. I would imagine it would be able to monitor everything as I’m not even sure if a PO had the left side dash indicators connected. As I look under the dash I can see the harness and it appears to be connected. Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
cruiser54 Posted August 11, 2019 Share Posted August 11, 2019 If the PO used an HO intake gasket, you could very easily have a vacuum leak between the intake manifold and head. At idle, spray that area with carb cleaner to diagnose. Do the Tips!! And here's what you need to know about HO vs Renix: HO myth buster Renix in 90 made 182 HP. HO in 91 made 190 HP. That's 8 HP difference. HO only made more HP than Renix at higher RPMs and not a bit more torque. HO had a 58 mm throttle body versus a 52 mm throttle body on a Renix. That’s 20% more air available through the HO throttle body. The HO also had a better design header. See where I'm going with this? It’s only a 4% horsepower increase….. The whole 8HP was not mostly from the head, but from the bigger TB and better exhaust manifold. Put a 60mm TB from www.strokedjeep.com on your present manifold using the Renix head, eliminate the "crush" in your headpipe with proper re-routing, and go for it. HO stands for Highly Overrated. __________________ Link to comment Share on other sites More sharing options...
Pete M Posted August 11, 2019 Share Posted August 11, 2019 We have a member in the vendors section of the classifieds that bores out throttle bodies a Renix era full gauge cluster will swap right in and give you a tach too. no wiring needed. just swap the 2 sending units and go! Link to comment Share on other sites More sharing options...
JustEmptyEveryPocket Posted August 11, 2019 Share Posted August 11, 2019 3 hours ago, Pete M said: a Renix era full gauge cluster will swap right in and give you a tach too. no wiring needed. just swap the 2 sending units and go! This is what I was going to suggest as well. So much cleaner and easier than do it yourself. The structure is already there in the truck, you just need to change two switches to sending units and swap the cluster around. Easy as can be. Link to comment Share on other sites More sharing options...
donald.wade3 Posted August 11, 2019 Author Share Posted August 11, 2019 This is what I was going to suggest as well. So much cleaner and easier than do it yourself. The structure is already there in the truck, you just need to change two switches to sending units and swap the cluster around. Easy as can be. I have checked around but need to do more research first. It was the initial plan but again have to find the right cluster as far as speedo gear and tach setup and so on. Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
JustEmptyEveryPocket Posted August 11, 2019 Share Posted August 11, 2019 Good step by step process HERE including photos and part numbers. Check on here for people selling clusters. You can also find them on eBay or check SearchTempest. Link to comment Share on other sites More sharing options...
donald.wade3 Posted August 12, 2019 Author Share Posted August 12, 2019 Good step by step process HERE including photos and part numbers. Check on here for people selling clusters. You can also find them on eBay or check SearchTempest. I do appreciate the help from all. This is a learning process for me for sure. Looking forward to all the knowledge and willingness to help. Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
Eagle Posted August 12, 2019 Share Posted August 12, 2019 3 hours ago, donald.wade3 said: I have checked around but need to do more research first. It was the initial plan but again have to find the right cluster as far as speedo gear and tach setup and so on. Not much research needed. "Type 2" clusters, used from 1988 (or late 1987) through 1990 have a potentiometer on the tachometer that allows calibrating it for 4-cylinder or 6-cylinder. There is no need to change the speedometer gear unless you change the axle gearing, or make a LARGE change in tire size. Link to comment Share on other sites More sharing options...
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