Oil and tranny coolers, particularly Chevy

[booster]

Our 07 C190P Roadtrek is very typical of the Chevies (up to at least the 6 speed change anyway) in that it has a tendency to run hot on long climbs, or stop and go. It started out as a non towing option van, so no extra trans cooler, but with oil and trans coolers in the radiator. Once we had a Scangauge it got pretty obvious it was getting hotter than I was comfortable with, which would be about 210* on both water and trans, and we saw 220* quite quickly sometimes. Added a Chevy OEM cooler, with minimal benefit, I think. Put in a 2000+cfm Spal fan in front of the AC condenser but behind the trans cooler and that helped a noticeable amount. Added a second Spal fan and closed up all the air bypasses around the radiator and got a larger improvement, and that is where we have been for a while. It really is more of the trans temps now, with the water secondary. What was of particular interest was that the electric fans made a noticeable difference at 60 mph in both trans and water temps, and the normal rules say fans don't do any good above 35 mph. To me that meant air restrictions somehow.

To get better water cooling, it made sense to get all the extra heat from the trans and engine oil out of the radiator by going to standalone oil coolers. The norm for doing this is to mount big cooler underneath, with big fans on them, but space and packaging made that a not very attractive option. I went looking for information about putting the standalones in front of the radiator, and really had a hard time finding any decent information on sizing them properly. Nearly all the information is based on how heavy you are, or how many btu you need to get rid of, with no other attachment to reality. The only real information I found was from Setrab, for engine oil coolers only, that based the sizing on how many horsepower the engine would actually be running at when the max cooling was needed, and that allowed me to size that appropriately, I think. Almost all the manufacturers just tell you to put in the biggest trans cooler you fit, when you actually contact them, as they don't have a clue beyond that. When I contacted Setrab, the application guy I was communicating with was very interested when I asked why they didn't have a similar hp chart for transmissions, as that is what really counts because a relatively constant % of the power is going to be lost in the trans to heat. They don't have such a chart, but expressed interest in going to see what they can find out. I hope they do as it would be a huge benefit to the dealers and customers. I had done some guesstimate calcs and come up with a btu number I thought might be close, and it was only one size below his recommended (based on experience not data) size. I had room for what he suggested so decided to try that size for the trans.

With no water heating of the oil and trans fluid, I did also get 180* thermostats for both the trans and and engine oils, as well as checkvalves to keep the coolers from emptying at every shutdown.

From here it is pretty straightforward, just finding a good place for everything. Two coolers, two big fans, two thermostats, two big checkvalves, and a bunch of AN fittings and stainless hose in 06 size for the trans and 08 for the engine oil.

I found that I was best to swap the side of the van for the coolers, so the trans in on the driver side and engine oil on the psg side. This give room for the thermostats and checkvalves by running the crosswise below the radiator inlet area. I mounted the thermostats and checkvalves to a piece of 2X2X.125 aluminum angle that bolts up to the bottom of the frame rails just behind the bumper and ahead of the radiator. It is all built as bolt in subassembly.

The checkvalves point opposite directions and cross in the middle. The two oil circuits are offset on the angle to clear each other

This is one of the thermostats

Here the assembly is mounted in place in the van, with hoses, in the checkvalve center area.

 

[booster]

Nothing particularly special in mounting the coolers, and left the fans where they were. It is nice that the fans will blow through the condenser and radiator and also such air through the oil coolers, so we get double use from them. I just made some top and bottom brackets to hold the coolers. They do not touch the fans or radiator at all, which IMO is important from a vibration standpoint.

Everything in place.

From the psg side, so can see air baffles.

This shows the clearances to the fans and grille, and it is close to both.

This is the redone bottom air baffle that now has to let 4 hoses and the center fan support through. While I was there, I changed the connectors on the fans from the Spal Molex style to Delphi Weatherpacks.

 

[booster]

The engine oil lines have to snake past a lot of steering parts, and needed a support in the driver side wheel well area.

Trans lines were much easier on the passenger side, just a simple anitbounce support.

All tucked in behind the grille.

All done.

 

[booster]

Of course, it doesn't say Chevy on it anymore, either

The stock Chevy grille has always kind of made me wonder, as it had so much blocked area by the big center bar and coarse crosshatch. I think it may be at least part of why the fans helped even at higher speeds.

I measured the clear air area of the Chevy grille, and it is only 45%. The GMC grille looked to be much more open, and it is, measuring in the low/mid 60s% range, so about 40% more clear area than the Chevy grille. Will it help, we will see. I should be able to see a difference in how much the fans help at highway speed if it does improve things.

This is all not really a cost effective, cost justifiable, modification, as we were able to get by OK without doing anything more. The gains will be in climbing speed, I hope, and in traffic, mostly in not having to watch for temps climbing, if we see good improvements. More enjoyable drive type benefits. I am also hopeful I will be able to fill in some of the blanks that are in the available information on the whole issue, including the grille open area questions. I used AN fittings and hose to be secure, even though the cost is quite high. I have never had an AN hose fail, even after 20+ years of turbo engine use in our old Challenger V8.

I chose the Setrab coolers because of the size first as they are just right to mount vertically, and they also have a sterling reputation, and were much more technically helpful and knowledgeable. I got a 915 for the engine oil and a 925 for the trans oil, plus two of their thermostats and fittings and hose. The checkvalves came from Summit. I was going to use Derale initially, or Earls, but the sizes weren't the best fit, and Derale quality has apparently badly slipped lately, and it was mentioned several places that the had changed suppliers.

Now we can't wait to get to some mountains. Maybe a test in rush hour traffic

 

[peteco]

Great mod. I bought the GMC grille a few months ago for the same reason: more open than the Chevy. I have not installed yet. I will do that and see what that one change does.

 

[booster]

Were you able to find a decent used grille, or go aftermarket?

 

[BBQ-ClassB]

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+1

+1

+1

 

[peteco]

Were you able to find a decent used grille, or go aftermarket?

http://www.autopartswarehouse.com/sku/Replacement/Grille_Assembly/G070116.html

Price has gone up. It had been $149. Got 15% off that as first time buyer. It does not have the GMC logo. I plan to remove the Roadtrek logo from the hood and put it where the GMC logo goes.

 

[booster]

Have you taken a good look at the the grille yet? I got two of the aftermarket ones that were badly broken in shipping, or maybe even before.

The markings and inserts on them indicated they were made in Taiwan and distributed by Sherman, who sells is huge into aftermarket and rust repair panel and such. On edit-I just looked at the broken remains and it has a molded in name of Profortune in Taiwan. If yours is the same, take a very good look at all the reinforcing ribs. Even if not in one of the completely broken areas, both grilles had big broken out pieces of the ribs, particularly around the lower mounting towers that get the clips on them.

Ours came in a coffin sized box, with the grille in a big plastic bag, with a layer of thin foam. At least the bag kept all the broken off plastic ribs and mounts from rolling around

 

[Ron J. Moore]

Wow, I really look forward to the "magical" mods you have achieved over the years. That garage of yours is really a "RT Improvement Center." Thanks for sharing, Ron

 

[peteco]

Have you taken a good look at the the grille yet? I got two of the aftermarket ones that were badly broken in shipping, or maybe even before.

The markings and inserts on them indicated they were made in Taiwan and distributed by Sherman, who sells is huge into aftermarket and rust repair panel and such. On edit-I just looked at the broken remains and it has a molded in name of Profortune in Taiwan. If yours is the same, take a very good look at all the reinforcing ribs. Even if not in one of the completely broken areas, both grilles had big broken out pieces of the ribs, particularly around the lower mounting towers that get the clips on them.

Ours came in a coffin sized box, with the grille in a big plastic bag, with a layer of thin foam. At least the bag kept all the broken off plastic ribs and mounts from rolling around

Mine is made in Taiwan also. It arrived unbroken. Have not installed yet.

 

[booster]

Sounds like your delivery guy was less of a hack than our Fedex one was. Both times the box showed up on the front steps standing on end, and the grille had essentially no support in that direction, so it took a hit when plopped down, hard. The first one had one whole end broken off, on the second, both ends had flexing damage like broken ribs and broken off mounts, but the entire ends were still in place.

The grille in the pix is the second one, after half a day of "plastic welding" it back together with a soldering iron and then reinforcing with ABS plastic sheet material I had here for splash guard making. I wanted to be able to get at least some information with the GMC grille. I have no confidence it will hold together against the rigors of the road, but you never know. I still need to get out and look at one that is in a junkyard about 50 miles away from here. It is off a 2003, though, so could be a bit on the rough side.

The grille swap is a quick one, normally, but can be a bit tough if the push clips stick. It is held in with 4 bolts, two on the top edge, and one behind each of the turn signals (pry out outboard end of the signal lamp and unhook the inside to remove). The headlights normally can stay in place, but it is only a couple of screws so I usually remove them two for more room. Once the bolts are out, there are just the 4 clips holding the grille in place, two across the top and one in each of the lower corners on the little pedestals of the grille. The service manual says to just pull the grille out, but I know ours would have broken it was so tight. They use the same clips that are on the dash parts, which can be very tight. The top clips can be easily pried out with a screwdriver, and then the grille can be moved out at the top enough to get a long screwdriver down to pry out the clips at the pedestals, which were the really tight ones on our van.

Going back in, I usually give the clips a squeeze with a pliers and do a trial fit in the slot they will go in, before putting them on the new piece. That way, you can get them so they actually pull in and out easily like GM claims they do (a little silicone grease also helps.

I did also had to grind off a bit the chrome insert at the upper outboard corner, as it interfered with getting the headlamps back in.

 

[booster]

I got out for a ride in the van yesterday, about 30 miles of typical flatland with moderate wind.

Everything looked as expected from the cockpit, with the oil temp leveling off at about 150* at 55mph and 160* at 70mph, both below the oil thermostat setting. Kind of expected at 50* ambient that I was in.

The trans temp settled at 167* degrees at all speeds, so it had to be running on the thermostat at all points, and was very stable with only minor variations at speed changes until it resettled.

The only surprise I had was after I got home and jockeyed around backing into the garage, which always take a while. I poked my fingers though the grills to feel the coolers, and as expected, the oil cooler was not very warm at all. The trans cooler, however was completely heated up, inlet and outlet, so it had to be getting significant heat and fluid flow. At 50* ambient I expected it to be cooler. I hope this isn't a sign that the cooler is not large enough, but it will take more testing to see about that.

 

[markopolo-ClassB]

You know that I'm no expert in this at all but the trans temp seems on the high side to me with the cool ambient and short easy run.

The trans temp in my van is always lower than coolant temperature whether towing or not, short runs or hours of driving with long hill climbs - it's always lower. That's using the Scangauge for monitoring.

 

[booster]

You know that I'm no expert in this at all but the trans temp seems on the high side to me with the cool ambient and short easy run.

The trans temp in my van is always lower than coolant temperature whether towing or not, short runs or hours of driving with long hill climbs - it's always lower. That's using the Scangauge for monitoring.

That was my first impression also. Because of the thermostat in the line to the cooler the actual 167* was not of issue, as the thermostat is made to hold the temp up in cooler weather. What was the surprise was how warm the cooler itself was, which would indicate that it was getting quite a bit of the fluid. The hard part is that you don't know how much fluid the thermostat is bypassing compared to what it is sending to the cooler.

We don't have big hills around here, so I will have to get into some stop and go traffic to run up the trans loads and temps and see what happens.

This is a big cooler at over 50K btu capacity, so hard to imagine the single tube in the radiator could do that much or more, but who knows.

 

[booster]

We are trying to get away to Duluth for a day or two to test more on the trans temps. It is supposed to be 80* here, but much cooler there unfortunately. Lots of very steep and long hills in the city itself and a long climb out to the south on the freeway. Hopefully will tell us something useful. With the trans cooler position in relation to the cool grille air and with the fan right at the cooler, I think we will see lots of benefit from the fan.

 

[booster]

I am starting to believe that either our Chevy is an anomaly, or there is a lot of information on transmission cooling that is less than stellar.

We just got back from a trip to Duluth, Mn so we could test cooling on some very steep lower speed hills, as well as do some stop and go in smaller hills. We can see trans temp, engine oil temp, water temp, and alternator temp (which is a good indication of how hot the air is after leaving the radiator into the engine compartment.

Trip up about 120 miles of freeway, trans at 167-168* (on thermostat), engine oil at 158-159*(slightly below thermostat). Ambient about 65*. These are the same as I have seen before. We got to Duluth and went right into traffic stop and go, so still carried highway heat. In the stop and go driving, the trans temp DROPPED to about 156* and the water temp an alternator temps went up a little (so radiator running hotter). We all know that the trans and water get hot in traffic, but it didn't happen in this case. All I can think of is that normally the trans isn't getting hot from it's own heat, but from the water getting hotter in the radiator and warming the trans fluid, or not cooling it much. This was a complete and total surprise to me.

We then went to the hills, climbing a few in succession. We saw a bit of climb in both the trans and the water while climbing, with the hottest we saw the trans was at 185*. It happened after a steep climb and then an immediate stop at a red light, so reduced airflow to the cooler. Water temp got up to 195* so only a few degrees increase. All was done with the two auxiliary fans off, except at the redlight when I turned them on to see what would happen. It dropped the trans temp 6 degrees in about a minute, which is way faster than they would cool the trans when it still went through the radiator, too. This would back up the water having a big controlling input for the trans temps.

It was cold in Duluth, so the temps were in the 50's, so not as good as if it was hot out, but still decent information. It at least confirmed that it is probably OK to head to mountains in the next few months. We will learn more there for sure.

One thing I did like a lot was that the trans oil thermostat held the oil temp constant nearly all the time, and got it there quickly at startup. We used to see 110-130* trans temps when it was 50* or cooler, which is lower than I would prefer, but the 170ish we get now is right about right, especially for DexronVI.

The much quicker cooling of the trans fluid when then fans are on, or the load is reduced is also a plus. Major changes in temp are now looking to be in a couple of minutes, but it used to be closer to 10 minutes to get cooled down.

 

[peteco]

Finished my Chevy Roadtrek grille upgrade to the Savana van grille. Made separate post here:

http://www.classbforum.com/forums/f8/chevy-roadtrek-grille-mod-6601.html#post58415