Can someone tell me which line from the trans to the radiator is the pressure side and which is return, on a '99 Jimmy? I want to install a cooler in the return line and a transmission temp gauge in the pressure line where the fluid should be at it's hottest. I am also interested in opinions on how best to run the cooler. Some guys say before the radiator, some say after the radiator, some say bypass the radiator all together. What say you?

I would only bypass the rad if you have a monster of a cooler. I believe that's what Dodge does with some of their big pickups.
Sorry I don't know which side does what

Thanks OBP. I think I will try to put the cooler in the return line from the radiator first. I'll put the gauge in the pressure line to the radiator. I'll just pull the top line off and start the car. If juice comes out the line that's the pressure side. If juice comes out the radiator it's the return side. If I find I've got 150 degree fluid going to the radiator only to be heated up to 195F I'll bypass the radiator. I got a B&M 24000 GVW cooler from Shawn on here. It is not huge, about 8 inches by 10 inches. When the alternator went out the other night, I had a good talk with the tow company owner about pulling that big hill (3 miles, 7% grade) between here and work with a load. He said the most important thing to him is the ability to lock up the torque convertor. He showed me temps over 250F that fell to 165F within 500 feet of him locking up the TC. I played around with the Tow/Haul button tonight coming home from work and I'm pretty sure it is locking up the TC when you activate it. I will see more and post again when I get the cooler and gauge in and run the mountain a few times with and without the boat on.

I'm looking forward to seeing your findings, and might copy some of your work. I don't think that I can lock up the torque converter on my 85, but since I tow a trailer through some steep trails I'd like to help it run cooler.

I was thinking about getting the exact same thing for my 97 blazer. I wanted to do a trans temp gauge and cooler. What do u do to get the trans temp. Like what gets wired to find the temp or is there like a sensor that gets put in or on the line? Any one know

I would make a T fitting out of plumbing parts that'll allow me to splice into the oil lines, and get a 2 wire oil temputure sending unit for this setup (The second wire usually goes to ground, since the T probably won't be grounded when your done). Run the gauge inside wherever you want it, and wire it up according to the hopefully enclosed instructions.

can i cut out a large section of the metal trans tube, and use a heavy duty rubber hose to make up the differnce with a t fitting spliced in that, or should it be a metal splice?

My plans are to just use rubber transmission hose. Rubber fuel line isn't designed for the temputure of the transmissing oil so make sure that it's transmission hose that you buy. They look the same to me.

Thank you once i get done school, that will be one of the first things done

We had it in front of rad passenger side with the connections like facing vertical not horizontal.


How did it get to ya? I thought all trans fluid was out but i noticed before shipping it wasnt haha i dont know how so i bagged it.

I try usig 20 lbs of compressed air or so to clean out of such things

I dont have compressed air haha. Link to the cooler man got haha minus 99 percent of the install kit, it was used on truck.
http://www.amazon.com/gp/product/B0006HM85M/104-4611499-4187134?v=glance&n=15684181

Heres an article with a pic on install:
http://www.hotrod.com/techarticles/44618/

You must have added a tow/haul switch on the Jimmy cause I never saw one on the S-10 size Jimmy/Blazer before, only full size. GM states never use "D" or overdrive when towing heavy loads due to heat so put it in "3".

Great article Muddog, I did a Google on trans cooler installation last night and found several like it. The cooler goes in the return line according to most of the articles. That's where I'll put mine. The Jimmy came with the Tow/Haul button from the factory, if it was an option I can't say. It was a lease vehicle and I bought it from the second owner.
I plan to use a 1/2 or 3/4 "T" reduced down to accept 3/8 hose fittings plumbed into the pressure line as close to the trans as I can get for the gauge. I may bring the gauge wire up from the bottom thru the trans hump if it will come up thru there easier. Ideally I would pull the trans pan and take it to work and have a half coupling welded in and then put the temp probe right into the pan. If I ever get the pan off and can do without the car for a while that's what I'll do and then move the probe. The reason for reducing down a bigger T is to make sure I get the probe into the fluid flow without restricting it.
Blazerman the cooler got a few layers of shrink wrap from somewhere to seal it up, so it arrived in good shape, with a pretty soaked envelope but the package was intact. I want to get the cooler on but I'd like to put the gauge in and run it a week, then put on the cooler to see what difference it makes. I'll take some pix of the gauge setup and try to post them.

Ideally I would pull the trans pan and take it to work and have a half coupling welded in and then put the temp probe right into the pan.

What a good idea, I never thought of that.

I've got 2 vehicles, so I can afford the down time, I think that I'll use this idea on mine.

That way I'll also be able to drain the transmisssion oil easily when I want to.

I wouldn't mind also having another gauge in the return line

Yes lol yeh i had a bag around it but i dont know about usps haha

I think we should rethink the sensor installed in the pan. It sounds good at first, but I Googled around a little more this evening and someone pointed out on an auto trans site that the the pan fluid has been cooled and is in the reservoir waiting to be used again, it is at it's coolest right there. Every installation I saw put the gauge in the pressure side of the trans cooling lines, before the fluid had been thru the radiator or aftermarket coolers. This is where you will see your hottest temps and the place to put your gauge, according to the tranny site. I got the gauge today for less than $20 at Advanced Auto. I will rig the T assembly tomorrow and try to install it and maybe the cooler this weekend. Takin' pix as I go.

Moser,

Why are you installing a tranny cooler?

Are you towing?

I tow a 17 foot Starcraft Superfisherman. I have to hump it up over a big mountain with a 3 mile 7 or 8 % grade. I have cooked 4L60E transmissions in GM 1500 trucks twice pulling this boat, and plowing snow. I put coolers on each of the 1500's after I rebuilt the transmissions and had no more trouble. I went to the Jimmy to try to save a little on gas on my 100 mile a day commute. That part is working my average having gone from about 13 with the GMC truck to about 17 in the Jimmy. I think the 4.3 is up to the task of towing, I am trying to protect the trans a little with this cooler and gauge. I still plow, but use the guy I work for's equipment now.

I don't think that I've ever driven a Blazer or a S10 with a 4.3L, but I've driven some 1/2 ton's with them in and they're powerfull little motors. I don't think that you'll have any problems towing that boat If you do a mild cam swap will cure the problems.

I tow a 17 foot Starcraft Superfisherman. I have to hump it up over a big mountain with a 3 mile 7 or 8 % grade. I have cooked 4L60E transmissions in GM 1500 trucks twice pulling this boat, and plowing snow. I put coolers on each of the 1500's after I rebuilt the transmissions and had no more trouble. I went to the Jimmy to try to save a little on gas on my 100 mile a day commute. That part is working my average having gone from about 13 with the GMC truck to about 17 in the Jimmy. I think the 4.3 is up to the task of towing, I am trying to protect the trans a little with this cooler and gauge. I still plow, but use the guy I work for's equipment now.

There are two options I would consider:

1.) Use a separate tranny cooler and just cap off the connections to the rad. Remember that this can cause your transmission to take a long time to warm up when cold and could cause some line pressure issues and potential damage.

2.) You can connect it in series with the existing rad cooler. This will cool the fluid more than stock, but not as much as a separate cooler. But you will still have the ability to warm the tranny fluid up faster during the colder months.

The only thing you have to watch is that you won't be putting too much restriction in the tranny cooling system with the double duty cooling.

Just throwing my 0.02 out there.

I've had 2 vehicles with this trans and a cooler in the return line from the radiator, both seemed to work well. One of the reasons for the gauge is to allow me to watch for spikes in the temp. If I can't maintain satisfactory temp with the cooler in the return line I will try it with the radiator bypassed, or I will add a fan to the cooler. I thought about restriction with the cooler, and the gauge set up. B&M makes a lot of coolers so I guess I will trust that they don't cause enough restriction to hurt anything. The gauge will use a 1/2 NPT T. The T has about a .600 waterway hole thru it. The probe is about 5/16 to 3/8 in diameter and sticks about 60% of the way out into the waterway. There is plenty of clearance around the probe. I'll try to post some pix before I get it in so you can see the setup. I found 1 barbed 1/2 NPT fitting and 1 barbed 3/8 NPT fitting at work so I had to use a 1/2 X 3/8 bushing to get the second end down to the 3/8 ID hose size. The smallest diameter the fluid will have to find it's way thru is the barbed fitting ID at about .300. This is the same diameters as the B&M cooler fittings. All of my fittings came out of scrap bins at work so I can't say what they would cost. All of them had concentricity issues that put them out of tolerance for us to sell, but made them perfect for my application. As always, get permission before removing anything from your workplace. I'm serious about that guys. Your boss will almost always give you something you ask for if he can. He will also almost always have to fire you if you get caught stealing. I have to work Saturday so I may tackle this on Sunday PM. Unless I have to go fishing again.:grinyes:

Well this cooler and gauge are in the Jimmy. The return line is the top line right under the radiator cap. The pressure line is the bottom line all the way back to the trans. I broke the pressure line right at the bell housing and ran the gauge through the floorboard on the passenger side. I went through the floorboard right under a bundle of wire under the rug and insulation. I broke the return line right under where it goes in to the radiator and ran the hoses through the plastic around the radiator next to the battery. I took a bunch of pix, and will try to add them to the post tomorrow night after work. I started at about 2PM and finished at about 8PM. I had a couple of false starts and had to run to the parts store a couple of times, so you could probably knock and hour or so off the time if you start with everything you need. I'll post a parts list with the pix.

Well this cooler and gauge are in the Jimmy. The return line is the top line right under the radiator cap. The pressure line is the bottom line all the way back to the trans. I cut the pressure line right at the bell housing and ran the gauge tube through the floorboard on the passenger side. I went through the floorboard right below a bundle of wire under the carpet and insulation. I put the wire/tube in piece of gas line hose to protect it. For the cooler I cut the return line right under where it goes in to the radiator and ran the hoses through the plastic around the radiator next to the battery. The cooler is mounted on the passenger side of the radiator. I took a bunch of pix, and will try to add them to the post tomorrow night after work. I started at about 2PM and finished at about 8PM. I had a couple of false starts and had to run to the parts store a couple of times, so you could probably knock and hour or so off the time if you start with everything you need. I'll post a parts list with the pix. UPDATE: I typed this on Sunday night but the server was down for something and I could not post. Today on the way to work the Jimmy overheated and cooked all the coolant out in the parking lot at work. I put a can of Stopleak and 3 gallons of water in it after work and got it to my cousin's place to see what's up now. I hope it is the waterpump he put in a couple of weeks ago which is under warranty. With the car full of water and diluted dexcool it ran the 50 miles home without incident, and with the engine temp gauge in the normal range. It was leaking from somewhere but I couldn't see where and will let him figure it out. Trans temp gauge worked well on the way home. The temp fell about 40 degrees in 5 seconds after I hit the tow/haul button on the big hill. It climbed steadily from 140 to 190 til about half way up when I hit the button. It fell back to 145 almost faster than you could see the gauge move, after I hit the T/H. With T/H off cruising at 50 mph with torque convertor locked up it is at about 130F, touch the brake pedal and unlock the convertor and it shoots up to about 160F. The most interesting thing about having this gauge is to see the big changes in this temp that happen almost immediately when the TC locks and unlocks. The towtruck guy from my last break down, said the only thing in the trans that can make heat is slipping clutches and the torque convertor is the biggest clutch in the machine and it slips almost always. Now I want to take a piece of tubing and bypass the cooler to see how much hotter it runs without the cooler. I'll get these pix on if I can tomorrow, and report more when I know more.

Just for your future knowledge.

Do NOT put that stop leak stuff in your engine again.

It can also plug cooling jacket coolant pathways as well and can cause more damage than it will help.

I would replace your rad cap, chances are it is not holding the 16psi pressure needed to keeping the boiling point high.

Also, flush your system out ASAP and get rid of the stopleak.

Hmmm. I think I read an article where they had a by pass valve that open to the AUX cooler when the oil reached a certain temp to help control warm up problems. Will have to look.

Looks like the first post worked after all. LT thanks for the advice, but at 1AM, 50 miles from home after the entire cooling system bled out in about 2 minutes, I will always try ONE can of BarsLeak. I have never had any problem (in 37 years of driving) with using ONE can of stopleak products. The problems come when you try to dump a can in every other day to keep from fixing something. The 13 qt system took 12 quarts of water after it cooled down for 9 hours. It never got real hot. The check gage light came on for about 5 seconds and I pulled into the lot at work. After work I filled it up with water and 1 can of stopleak and it held all the way home. The problem was a gasket on the water pump they just put on, so my cousin fixed it today, no charge. He drained it all out today and filled it back up with new 50/50Dexcool. The engine temp gauge has never shown any temp above 200 in all the time I owned the car, with the exception of about 3 minutes yesterday. I flushed it out with the Prestone 3 hour product and replaced the cap with a 17 pound cap from Advance Auto right after I started driving it a month or so ago. I lost the water pump 2 days later. I think I am done using flushing products. I'm not losing any coolant or having any problems keeping the temp low with the original 12 pound cap, so I'm going back to it. As long as I don't have any trouble I'm not going to subject this system to the higher pressure of the 17 pound cap. If I get the system cooking off alot I will put the 17 pound cap back on. I'm trying to get the pix from the cooler/gauge install uploaded to Photobucket, but out here in the sticks where we only have phone lines for the net, the uploads take about 5 minutes each. When I get them all on there, I'll post them here. The Jimmy's back in commission and the new gage and cooler are a good addition. We're taking a used '06 Pontiac G6 GT for a 24 hour test drive tomorrow and Thursday. So much for driving the Bonnie 'til it won't go no mo.

You cannot blame a rad cap and a flush for your problems, it uncovered a weakness that was there. Kinda like when someone switches to synthetic oil and says it caused an oil leak. The leak was there, the clean running synthetic removed the sludge plugging the opening.

It isn't the oil's fault, the leak was already there due to negligence.

Hope you get my point.

The stock AC Delco cap is flawed and won't even hold 12psi.

The gasket will harden and cause problems and it won't seal.

This will cause it to suck air in through the cap instead of coolant from the overflow tank which will cause your dexcool to turn acidic which will start to eat out things like water pump seals and other cooling system components.

Trust me, the stock cap is not 12psi, it is 15psi, and having a cap lower than the recommended rating will not do any good even when coupled with the fact it is flawed. The pressure is needed to keep the boiling point high.

Most of the dexcool problems were not caused by the coolant, they were caused by a factory flawed cap with a piss poor fibrous rubber seal.

So if I hadn't messed with what wasn't broken and the "weakness" had never come to light would it still be a weakness?

It would have probably gone anyways, it might have just taken longer.

I know what it's like living in the sticks where you sometimes have to do temp fixxes, and yes I have used Bars to get me home and it worked.
However I bypassed the heater core first to ensure that I didn't plug it.
I don't mind working on the motor but if I can avoid pulling the dash I'd really like to.

Plus I've flushed the system out afterwards.

So if I hadn't messed with what wasn't broken and the "weakness" had never come to light would it still be a weakness?

It would have still come up, but just later.

I would upgrade your rad cap ASAP though. I have a 16psi and it has been working flawlessly.

I was loosing coolant all the time and since the cap replacement, not a drop has been lost.

Its like 5 bucks just do it.