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My current project 80 Camaro with an LS3. I bought a vacuum radiator purger from Harbor Freight. Has worked well. So maybe trapped air? I always drill a couple of 1/8" holes in the thermostat to let coolant thru.
I realize this thread is long, and very old, but thermostat changes and purging the air have been done several times. Might be worth revisiting and I appreciate any ideas at this point...
I didn't see any pictures of your engine bay, but the others that were posted looked rather cramped. That said I have worked on many swapped vehicles. A couple of them just didn't have enough airflow under the hood to let the radiator do it's job. That is easy to check for. Take off the hood and if it runs cool or cooler, the fan isn't pulling enough or it's just backed up in a cramped engine bay and can't escape. The removed hood is free to check. Good luck.
94 YJ with L33/5.3/Truck manifold, stock truck 3bolt TB, 4l65E/NP241C TCASE , Novak motor mounts with engine mounted to their spec in the YJ..
I have a full Metalcloak high rise tube fender kit.. I have the Aluminum fender liners, that leave a 2" gap down both sides.
Ebay imported 4 core radiator, driver side pickup, passenger side (Upper) return, My hoses each are about 50% steel 2" exhaust tubing.
My steam vent setup is front two ports (Rear plugged) no manifold connections, the vent tube is routed to only go up hill and patches in to a bung on the steel tube on the return hose.
Taurus Fan from Rock Auto (Delphi IIRC) . I trimmed the shroud of the bits I didn't need and built my own to get full flow across the back of the rad.
I have 2" between the fan and water pump pulley center..
4.56 gears, 33" BFG AT'/KMII's , Winch , tall custom bumper, and hella Rally 2000 lights in front of the radiator.
4.5" of total lift (Body 1" suspension 3.5)
Running a 180 thermostat.
Holley Terminator EFI.. so I have a two speed fan that responds very quickly.
70 MPH , 85 degree day, I run about 180 on the freeway. Pulling a heavy 5 mile grade to my house I am at 185 (Still 70MPH) ..
Unfortunately My issue is I had a leak and under-filled the 4l65 so I'm down waiting a new trans.
So theres a pretty close compare...
Does your jeep still have the black plastic air guard between the front frame rails behind the radiator?
Before the 5.3 my 2.5 with its tiny stock single core would overheat if I took that piece out..
The thread was an interesting read start to finish.
Looks like @Jeepthing is running a radiator that is too small for a V8 in my opinion, but also what about pulling the inner fenders to see if that helps?
My combo is in no way similar but mine (cammed 5.3, turbo, big a/a front mount in a '67 Camaro) ran super hot until I changed my fan settings and build a full shroud for it. I don't have inner fenders either, car came that way. Taurus fan. No stat, and I have wp bypass blocked off. Fan on at 195. 26x19 core). Guess my point is if I can cool this thing with the a/a you should be able to figure this out.
Thanks for the post, sounds like your setup is quite different for sure. The limited space requiring a smaller radiator isn't helping and neither is the cramped engine compartment.
@Pro Stock John You mentioned the fan "should not run below 30 mph". That thought process is opposite what I am used to. I would imagine the fan not running once you reach a certain speed, to prevent air damming, makes far more sense to me. Care to elaborate on that? Also you reference "a/a" which I assume is an air to air intercooler for your turbo setup?
My next steps are to verify the temperature the fan comes on, even though I've checked before and changed fans a couple times now. While doing this I want to see how air is drawn through the front of the Jeep and how much the transmission cooler is restricting air flow.
I am talking with Novak again to see if they have new information that might be helpful. They say the fan is programmed to turn on at 210 and off at 200, lowering those temps may be a good idea. I am running stock tstat and lowering the fan temps may be an issue if I go as low as 195. I also verified the fan does run at higher speeds as well which I don't necessarily like and more testing would be needed to verify. They also say the LS engines run at 210-220, which I am exceeding at this point at times.
I have removed some of the inner fenders and that did not seem to help much, there is more I could modify and may look into that as well. I cannot remove them completely as they do provide mounting for a number of accessories I cannot get rid of.
I am currently looking into a mechanical fan as every post mentions no overheat or high temps when using one.
[QUOTE=Pro Stock John;20472313]The thread was an interesting read start to finish.
Looks like @Jeepthing is running a radiator that is too small for a V8 in my opinion, but also what about pulling the inner fenders to see if that helps?
My combo is in no way similar but mine (cammed 5.3, turbo, big a/a front mount in a '67 Camaro) ran super hot until I changed my fan settings and build a full shroud for it. I don't have inner fenders either, car came that way. Taurus fan. No stat, and I have wp bypass blocked off. Fan on at 195. 26x19 core). Guess my point is if I can cool this thing with the a/a you should be able to figure this out.
Newer fans would be better than the stuff we/I am running. I'm running a 2 speed Taurus fan but only have the high speed wired.
Newer fans are variable speed, they increase as needed/programmed. One of these days I want to convert my setup over to these newer PWM fans. I've heard the C7 OE fan is a badass unit but I don't know if I can fit it.
The radiator core size is roughly 17" x 18" and per Novak's site the radiator is 22" x 18.5". I assume Novak is measuring total dimensions and not the core size. There is no space for a larger radiator unfortunately.
I am currently using Chrysler fan P/N - CBG4F250, from a Jeep Grand Cherokee as they are claimed to move 4,000 CFM, far more than the SPAL provided by Novak at the start of the swap. A two speed fan setup would be an improvement as I believe that is what the donor vehicle would have used (along with a larger radiator, two fans with one high and one low speed). Novak's programming is for a single speed fan if that was not evident by now...
I have my coolant crossover (4th gen) going into the top of my 5th gen waterpump.
I have my coolant hose area welded shut, and the internal bypass is blocked off by a disc. i do not run a thermostat.
I have my fan on at 195, off at 185.
I additionally bled my system by jacking up the front of the car 1.5 feet, so that the fill/cap was the highest spot. I put a funnel in the fill over night and coolant in the funnel kept adding as it bled. I bought a universal fill kit from Amazon that comes with different size caps so that the excess would not spill out.
My first 98 Wrangler LS swap was with a 4.8 truck engine with truck FEA that used a stock truck mechanical fan. I used a 98 Wrangler 4.0 HD radiator and fan shroud. No over heating at all. See pics.
@LS1 TJ Thanks for posting up some pics of your engine compartment. I have not found a single instance where someone running a mechanical fan has had cooling issues. You seem to be no different and hence my interest in ditching the electric fan setup. A couple questions if you don't mind as the mechanical fan option is getting more and more appealing.
I notice your fan has lots of room between it and the radiator, so much so it doesn't look to be inside the shroud at all. The front of your engine seems to centered on the radiator while the center of the water pump pulley on mine is a couple inches below the center of the radiator (engine mounts and body lift must be the difference). This could make a custom shroud necessary while yours is super clean with the factory radiator and shroud. Which engine mounts did you use and any body lift? I have Novak TJ engine mounts and a body lift, neither of which I am willing to change for many reasons.
I also see your intake uses what I assume is a stock piece that allows clearance for the mechanical fan. Any part number or details on that? I would likely have to go that route as the current intake tubing would not clear a mechanical fan.
I did locate a bad electrical connection at the fan and repaired with a new weatherpack connector. I believe this caused my latest issue of increased temps a week or so ago. I believe the fan worked for 3/4 of the trip but the connection failure caused the fan to stop working on the way home. When testing the fan was not turning on but after the repair the fan came on at 210 as it should per Novak. The odd thing is that the fan ran until engine temp hit 180 which is far lower than the 200 Novak claims it should shut off. The electric component of this is the other half of the interest in the switch to a mechanical fan.
Thanks all for the input and advice, hopefully making progress...
[QUOTE=LS1 TJ;20472607]My first 98 Wrangler LS swap was with a 4.8 truck engine with truck FEA that used a stock truck mechanical fan. I used a 98 Wrangler 4.0 HD radiator and fan shroud. No over heating at all. See pics.
My 98 Wrangler that I have now is the same one the in the pic above. The 4.8 swap was done 15-16? years ago. The 4.8 had a AX15 5 speed trans. Novak at the time didn't offer motor mounts. I've been to their shop in Logan UT a couple of times looking for install tips. Nice folks. I made my own from street rod mounts. Just kind of centered the engine and welded the mounts on after cutting off the stock 4 cylinder engine mounts.
I did see that the fan doesn't go into the fan shroud. A person could extend the shroud with a bit aluminum sheet metal. The 4.8 was unchanged from pulling it out of the 2003 1500 work truck.
No body lift on my Wrangler.
Currently my 98 Wrangler has a LS6/4L60E combo. I got tired of shifting. Novak radiator and a single no shroud 16' Spal fan. Has worked perfect for many years. I'm using the stock TJ temp gauge so it's a bit suspect but according to the gauge it turns on the fan at about 210 and off at about 190. The TJ was my second LS swap. I didn't want spend mega bucks on the engine/trans so I used all of the stock 4.8 truck stuff.
Yeah good connections are important. Correct gauge wires are also important as are really good grounds. For wire connections I use the heat shrink connectors with the goo on the inside that when you heat shrink the connector it creates a water proof connector. Never had a failure.
I hope the bad connection repair fixes your problem.
@LS1 TJ I appreciate you sharing your information! With my cooling issues having lasted for quite a while I don't believe the recent wiring issue to be my main issue. I am running a Novak wiring harness and other than the faulty connection at the fan, which was totally my fault, all connections and wire gauges should be appropriate. More trips will be done to see if this makes any sort of difference.
I'm surprised you are getting away without a fan shroud with your current LS6 swap. Everything I have researched says the shroud is critical to get air to draw correctly through the narrow Jeep grille. The fact you are using a Spal fan also confuses me, the CFM on those are 2,500 or under if I remember correctly, while the Grand Cherokee one I have now is supposed to be 4,000 CFM or so. I still believe I am having an engine bay heat soaking issue under load. The cooling system itself can cool the engine, however once under load for longer periods the engine bay is holding heat and the cooling system can't keep up. I have a hood vent panel which I question its effectiveness and have opened up the inner fenders a bit.
I also recently discovered my water pump has a very small leak. I believe the Jeep sitting for a couple years caused the seals/gaskets to shrink and now when the Jeep sits I see a couple drops of coolant on the garage floor. No leaks when running or the Jeep is warm. Looks like I will be looking for a new ACDelco water pump here soon. Would be the time to swap to the mechanical fan if I choose to go that route.
I have been looking into the mechanical fan swap and was curious what kind of CFM's they pull and am coming up empty. All I have found is posts by people claiming 10K CFM which would be great, but I cannot verify anywhere. My thought is the additional air flow over the electric fan would certainly help get hot air out of the engine compartment. Not sure if my thinking is flawed or if it might be the solution I am after.
Originally Posted by LS1 TJ
My 98 Wrangler that I have now is the same one the in the pic above. The 4.8 swap was done 15-16? years ago. The 4.8 had a AX15 5 speed trans. Novak at the time didn't offer motor mounts. I've been to their shop in Logan UT a couple of times looking for install tips. Nice folks. I made my own from street rod mounts. Just kind of centered the engine and welded the mounts on after cutting off the stock 4 cylinder engine mounts.
I did see that the fan doesn't go into the fan shroud. A person could extend the shroud with a bit aluminum sheet metal. The 4.8 was unchanged from pulling it out of the 2003 1500 work truck.
No body lift on my Wrangler.
Currently my 98 Wrangler has a LS6/4L60E combo. I got tired of shifting. Novak radiator and a single no shroud 16' Spal fan. Has worked perfect for many years. I'm using the stock TJ temp gauge so it's a bit suspect but according to the gauge it turns on the fan at about 210 and off at about 190. The TJ was my second LS swap. I didn't want spend mega bucks on the engine/trans so I used all of the stock 4.8 truck stuff.
Yeah good connections are important. Correct gauge wires are also important as are really good grounds. For wire connections I use the heat shrink connectors with the goo on the inside that when you heat shrink the connector it creates a water proof connector. Never had a failure.
I hope the bad connection repair fixes your problem.
I've done 10 LS swaps into various vehicles. 98 Wrangler LS6. 67 Nova (2) One with a built LS6 and another with a stroked LS2 to 427 cubes. 79 Camaro LS1. 99 BMW 3 series LS1. 73 Camaro L92. 99 Wrangler 6.0 LS. 71 Corvette LS1. 68 C10 LS6. And my current project 80 Camaro L92. All with a 16" Spal fans and no shrouds. Never over heated any time. Worst temps were 100 plus temps at the Good Guys car show in July with the big car show stop and go traffic. The fan cycled on and off a bunch but no problems.
I always run the biggest radiator I can fit. I've used Novak radiators for the Wrangler swaps. Then Afco and Be Cool radiators for other swaps really just depending on price and best size fit.
All my LS engines are pretty mild builds. Small cams and 91 octane tunes.
I agree I read all the time about LS swaps running hot but maybe I'm just lucky.
Just a thought of in regards to the 16" Spal fan. Here's a pic of the 99 Wrangler that I put a 6.0 in. The 6.0 was totally stock. Notice that the 16" fan almost covers the cooling fins from top to bottom. Some folks running dual 12" fans don't come close to covering all the cooling fins so the shroud is required.
Not sure if my 4.8 came from a van or truck. I'm almost sure it came from a truck. I used the stock truck FEA and water pump/fan. Stock spacing belt wise. No AC.
Just a note if anyone is doing a LS swap into a TJ and using a truck LS. The truck oil pan works. It does hang down a bit but its higher than the front axle assembly.
I would be the first to admit my Wrangler is a mall crawler. My summer top off cruiser and winter plow Jeep.
My 5.3L is an LM7 out of a 2005 Silverado and it uses truck accessories. I did swap the oil pan to a Tilden Motorsports reinforced unit as I do abuse this Jeep off road...or used to. I do have the A/C compressor mounted but have not gotten around to getting lines made so it's not functional currently.
I spoke with a local tuner, Eddie with Elite Performance and Tuning, who actually dyno'd the Jeep right after the swap years ago. He was very helpful and offered to take a look at fan settings etc. for me. Driving the Jeep yesterday the fan seemed to come on at 205 and shut off at 190. Different than what I found the night prior doing some testing. Eddie is way smarter than me obviously and I will report back what he says as I could be in better shape than I think.
@LS1 TJ You mentioned you have used Novak radiators in the Jeep LS swaps you have done. The last pic you posted of the Jeep does not look like you are using the Novak "cradle" mount they recommend. Is it a different setup, custom work, or am I mistaken?? Also, you mentioned you are watching engine temp via the stock gauge. From my experience factory "sweep" style gauges don't provide much info and I wonder what your actual temp is. I have a Scan Gauge II that I am monitoring engine temp, intake air temp, transmission temp, and fuel mileage.
Thanks everyone for all the time and input trying to help me out, it is appreciated!
12-06-2022, 04:11 PM
