'91 OEM HD Radiator... ?

I've got '91 Laredo with Towing Package and Heavy-Duty cooling system.

In the past, my Jeep always stayed between 190-200 ... even when sitting at idle during 100 degree weather. Over the past few years, it wants to run and creep into the 215-220 range.

No visible leaks and it's never overheated...


Questions:

How many cores in the '91 OEM HD radiator ?

Is it best practice to stick with the OEM HD unit upon replacement ?

Would a GDI or Modine cool better than the original OEM HD unit ?

I am not familiar with the HD radiator or upgrading the Jeep radiator and so I am not familiar with its quality or construction.

In general my thoughts with a good radiator that has seem some use is to first consider getting it cleaned (pickled?). However my understanding of the cost of upgrading to the newer system and replacing the radiator you have with a new GDI 4 core is about $150. Although there may not be a good reason for you to upgrade other than fixing your current radiator, why replace the one you have with another the same if you can find the new style for similar (or less money).

Sorry for not having any good specific info, just trying to provide my thoughts. A friend of mine just replaced his radiator with the stock one (1990) jeep and he paid more than he would have to upgrade the whole system to the new style. That just doesn't make sense to me.

Michael

A 1991, if I am not mistaken, has the open type cooling system. If that's the case, then there are really no "upgrades" that need to be done to the cooling system, PROVIDED that ALL SYSTEM COMPONENTS are up to OEM spec.

I would vote that you take the existing rad and either have it recored or replace it with an OEM equivalent. For an XJ with AC and/or the HD cooling, that would be two rows of tubes.

The GDI's, which feature 3 rows of tubes, seem to have a hit or miss quality record, and don't seem to deliver any more performance than a GOOD OEM type can do, assuming all other things being equal.

Of course a good cooling system should mean that you have good fan(s), good hoses, good thermostat, good water pump, and fan SHROUDS.

I have a '92 with all new or excellent condition OEM type parts, and with the AC on, in stop and go traffic, with the outside air temp at 115 degrees (I live in Phoenix), my coolant temp never runs over about 215-220.

That, in my mind, is an endorsement that the OEM equipment CAN do the job, IF it's up to spec.

Thanks for the feedback.

Yes ... getting it rotted-out would probably do the job and I could save a few dollars ... but how long will it last ??

I've read mixed comments on this site about GDI's ... fit and other quality issues. Since Mopar still sells the original HD OEM.... and it bolts right in with all the other surrounding parts ... well, I don''t want to change something I already know works---especially when new.

I would like to avoid having real bad cooling problems----I've been-there-done-that with aftermarket brake parts.

I was curious if anyone knows how many "rows" or "cores" the Mopar HD OEM radiator has ?? ... things are fairly tight in there now with the A/C condenser, trans-cooler, fans and shrouds.

I can't imagine trying to get a more robust unit in there.

I am about 90% certain that the Mopar HD radiator is the same one used in all AC applications. That's a two-row rad.

AZ Jeff....

Thanks! I didn't get to read your response since we posted at the same time.

Yes, it came with the upgraded cooling system ... 150K miles now.

I think I'll proceed with your recommendation and replace it. It's been flushed every 20K miles---the pump and t-stat was recently replaced.

AZ Jeff ...

What additional parts did you replace ??

Of course I will replace the t-stat again with a factory unit ... should the temp sensor on the t-stat housing be replaced ??

I'm not sure how far to go once in there.

On my 88 XJ there were two radiators available. There was a single core radiator and a doulble core radiator.

To get the double core radiator with the electric fan you either had the Facotory Air conditioning packager OR the towing package. So if your XJ came with either package you have the heavy duty cooling.

If you did not have either of these options then you had the single row/core radiator.

I was at my dealer and saw a modine radiator sitting there, I asked my mechanic about it and he told me alot of the time they get a modine radiator from the distributor in town today instead of waiting on the parts system to deliver one tomorrow. I have a GDI right now but think next time I'll install a Modine.

When changing the radiator I would also replace these items:
* Radiator cap
* Thermostat
* Fan clutch for the mechanical cooling fan, no good way to test it, they last about 5 years. Some aftermarket ones are too tall and are difficult to install.
* Upper radiator hose
* Lower radiator hose
* All the heater hoses
* Inspect heater control valve and replace if it seems worn out. You may have a plastic heater control valve so it may be smart money to install a new one
* flush out the heater core, Craig H has a write up on it, I can post the link if you don't have it.
* Install new stainless hose clamps, I prefer to get mine at the hardware store and not the auto parts store. Get a good brand like Ideal.
* new coolant and use distilled water. You may want to fill the engine a couple of times with distilled and drain to get out most of the old coolant. Also it helps to pull the coolant temp sensor in the head to let the air escape while you fill the block with coolant.

Things to consider while you have the radiator out.
* Replace the fan belt, it will be the easiest access you will ever have to the tensioner.
* Spin all the pullies and see if there is any roughness. I ended up changing the idle pulley by the AC compressor and the bearing for the mechanical fan. To change the fan bearing you have to buy the AC support bracket which was arond $75 at the dealer.
* IF your XJ has over 100K miles you may want to replace the harmonic balancer, the rubber fails and the pulley either walks forward or aft. Can really make your day. Mine failed RIGHT after I changed the belt and put in the new radiator. The harmonic balancer is mounted on the crankshaft.

On sensors you could test them if you have a ohm meter or digital multimeter. Just stick the thermostat housing in a large pan and bring it up to a boil. If you have a kitchen thermometer then check the resistance as the temp increases. This way you can confirm it working. This would be a good time to replace the temp sensor if you want to start a sensor renewal program. I replaced all my sensors and the XJ ran a little better every time a new one was installed.

I guess I lucked out -- I replaced my OEM radiator in my '88 XJ with a GDI and I got a good one -- no leaks, no dings, and excellent cooling. However, I bought it through a local shop and not through 1-800-RADIATOR. Don't know if that has anything to do with it, except the local guy told me they are selling them to us for less than what he pays the wholesaler, which leads me to suspect that GDI might be selling their rejects out the back door. However ... let me be very clear that this is nothing more than my personal speculation.

My real point in entering this thread is to mention that the OEM unit I took out was a Modine. And I know it was the OEM radiator because I bought the Jeep new.

Eagle, I think you did get lucky ... what's that saying: "timing is everything" and "being in the right place at the right time".

Since I work for a global manufacturer, I thought about your comment and decided to call GDI. Using discretion, what I learned is that "Transpro", formally known as "GDI", has gone through several changes over the past couple years.

I talked to a real nice old gentleman by the name of Elmer. He was very candid and addressed the quality concerns. He was well aware of the disatisfaction among Jeep owners and offered the following explanation:

As a result of several aquisitions, Transpro (GDI) sourced certain PN's to other global manufaturing sites -- namely China. Elmer was adamant he was NOT in favor of this decision. The company became aware of the quality issues and decided to take corrective action by changing the PN's and point of manufacture.

Currently, their OEM radiators are manufactured in Mexico -- so depending on when you purchased your GDI radiator ... and from a specific supply chain that could very well have a mix of new/old PN's in inventory, ... well, you possibly still could receive a bad one. My assumption is the variation in quality is hit and miss -- probably didn't warrant a recall.

The new (GDI) Transpro PN's are as follows:

4.0L 2-Row = 43-2335 (open system)
4.0L 3-Row = 43-6019 (closed system)
4.0L 3-Row = 43-6020 (open system)

Elmer commented these are copper/brass radiators now made in the same manufacturing site. If you request these PN's you should get a good product.


http://www.transpro.com

This is a useful thread, since I was just about to ask more or less the same questions about my 95 (original rad., with A/C which doesn't work), which has developed fin rot. It isn't overheating, quite yet, but it's running hotter than it used to. Obviously it isn't worth pickling, because the fins are blowing out. I was wondering whether I should opt for the GDI, but OEM sounds like the way to go.

I bought a 3-row GDI last fall, before being aware of quality concerns with GDI. I converted to the open system at the same time, and have had no problems whatsoever with it. In fact, it looked fairly good to me, with metal tanks instead of the plastic ones on the stock radiator.

The 3-row cools much better than the stock 2-row that was replaced. The temp gauge goes up to about 1/3 (180* thermostat), and stays there. The aux fan is controlled by an adjustable thermostat set to about 200*, but so far it hasn't come on.....

FYI:

I called Modine to inquire about their radiators. The tech engineer said they don't make a 3-core radiator for the 4.0L Jeep---a 2-core is the maximum to accomodate A/C condensor, fans, shrouds, etc.

When I mentioned that Transpro (GDI) makes a 3-core ... he commented the only way to fit a 3-core in a '91 Jeep Cherokee is to make the cores smaller---also citing he had never heard of Transpro or GDI.

If that's the case ... I don't think smaller cores and one (1) extra row would be much improvement over the stock 2-core---especially over time. You'd think they would plug easier.

I think I'm sticking to OEM HD 2-core----at least I know it's good for 100K miles.

You will have to check on this but I think the GDI and the Modine will have close to the same core thickness. I checked on the link you posted and the GDI has:
Core Size: 31 x 11 1/8 x 1 1/2

I looked up the Modine 2 core for my 88 XJ, the P/N is 1R2268 if is:
Core Size: 31 x 11 1/8 x 1 1/2

This means both radiators are 1-1/2 inch thick.

I am a mechanical engineer and know heat transfer is more of a black art than a science. There are trade offs for more rows of tubes and how much cooling you get out of each row. I could go into it but don't want people falling asleep reading my post.

If i was to buy a new radiator I'd buy a Modine right now. I am familiar with them from work, I also have a Modine Distributor in town and he can have the radiator that day or 24 hours at the latest.

I just recently installed a GDI 3-core. It was considerably thicker than the factory 2-core. But it fit with no problem, I also swapped out the fan clutch, water pump, thermostat and belt while I was in there. So far my aux fan hasnt kicked in at all(With exception of with the compressor) As far a durability, the factory one wasnt leaking, but some of the fins had started to rot out, however it had lasted 165,000 miles. I hope this new one will do just as good

On my 2-row that I replaced, there was a space where another cooling row would fit on the tanks. It was similiar to the 3-row GDI, except with one row missing. The GDI looked the same as the stock radiator, except the "empty" row was filled with another tube row. Everything else being the same, the (3-row) GDI shold effectively cool 50% better than stock.

It's my understanding that the Modine has larger tubes. I would suspect that a Modine 2-row probably flows/cools about the same as a GDI 3-row. Modine is a proven brand, and like Martin I would probably choose it if it was available.

I replaced my OEM radiator with a 3 row GDI over a year ago while converting my closed cooling system to an open system on my Comanche. So far, I haven't had a bit of trouble with the GDI. To be honest I was kind of expecting a problem although I can't pinpoint why. Perhaps it was because my GDI came with a plastic drain tap instead of a metal one. Kinda cheesy. Looking back, I suppose I should have saved some money and had my OEM radiator rodded out, but I wanted to convert to an open system anyway so what the heck.

BTW if anyone wants an '88 OEM radiator (presumably a HD radiator because my Comanche has factory air), I'd be happy to give it away. I've hung onto it because it seems a shame to dump all that brass into a landfill.

Erik
88 Comanche

Okay ... here's the facts about these radiators:


Modine "Open" 2-Row Radiator --

Modine PN: IR2802
NAPA PN: MO2802

Core Size: 31.5"x11.1"x1.5"
Tube Size: .625" (5/8")
Fins Per Inch: 17

OEM for Mopar/Jeep

Made in Wisconsin

==============================

Transpro (GDI) "Open" 3-Row Radiator --

Transpro PN: 43-6020 (current)

Core Size: 31.0"x11.1"x1.5"
Tube Size: .375" (3/8")
Fins Per Inch: 18

Made in Mexico

==============================

According to Modine "Fins Per Inch" is a critical specification. I realize there's more to it than this ... BUT ... if you simply multiply the tube size by the number of rows it should get you in the ballpark how much volume, flow or surface-cooling area the radiator is able to provide.

Modine: .625 x 2 Rows = 1.25"

Transpro: .375 x 3 Rows = 1.125"

In this case it appears the Modine has the edge with their 2-Row radiator. I also think in the long run the Modine will be more effective since they have 5/8" tubes, as opposed to the 3/8" tubes employed by Transpro.

What would you rather have in your home ... 1" water main or .75" main line ??

Purchased my first Jeep, a 96 XJ (154k miles on it) that was a sheriff's vehicle - is the GDI more suggested or would the 2 "oem" radiators do the trick?

BTW, forgive me for being a n00b to the site - LOVE MY JEEP though! look forward to going to joining a group in or around Wv for local Jeepin and someday attempt the MOAB

Go hit www.radiatorbarn.com and get either the 2-row or 3-row, all-metal. I would avoid the cheap ones with plastic tanks they are now offering. The oem is plastic tanks and they are prone to failing at the tank-core seam and can not be repaired. The all-metal ones are CSF brand which is decent quality. $156 for the 2-row, or $168 for the 3-row which is about 1/2" thicker in the core.