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Cooling System Overhaul - Stumped and Frustrated

It never goes over 220* now? Or is this without really loading it up with a trailer, etc?

I'd have to look at the mounting closely, and I think I said it before, but I wouldn't be surprised if the trans and/or oil cooler could simply be unbolted from the core support, and zip tied down a bit so the radiator was a bit less covered, for temporary testing.

I think that is a long shot, but a bunch of other things you've tried/tested since you started this thread have been too. As far as I can remember, there isn't anything you haven't tried that I would have tried (you try running with no t-stat?), other than moving the cooler(s).
 
dyeager535 said:
It never goes over 220* now? Or is this without really loading it up with a trailer, etc?
Click to expand...


It doesn't go over 220 unloaded, during normal driving.

Goes up steadily from there under any real load. :doah:

I hear you on moving the coolers. As soon as i get my bmw back on the road next week, i'll play with it.

Just can't justify hanging my coolers out of the front when i'm driving it daily.
 
One thing I have noticed on my two burbs (90 and 91) is that the dash temp gauge is much lazier and reads lower than actual coolant temps. If I tow and have the scan tool on them, it is funny to watch the actual coolant temp vary quite a bit, and the dash gauge doesnt even wiggle. On both burbs, the middle of the gauge, where it says 210, is 230 on my scan tool.

I guess where I am going is that maybe your gauge is accurate, and most others read like mine. In my half ton burb, I have a 205 stat, and the gauge reads the next line down from 210.

Has yours ever boiled over, or could you hear it bubbling in the overflow?
 
Hasn't boiled over, but have confirmed gauge readings with a Mechanical temp gauge in the head port on the other side of the motor.
 
Have you done the rag test to see if the fan will hold a rag against the grill with its pull? Have you
Checked to see that the ac condenser isn't packed with debris.
 
y5mgisi said:
Have you done the rag test to see if the fan will hold a rag against the grill with its pull? Have you
Checked to see that the ac condenser isn't packed with debris.
Click to expand...

Not sure the rag test will pass, but shouldnt' matter at freeway speeds.

AC condenser is fairly clean, but good tip to check it again.
 
I had a hot idea in regards to testing w/o the coolers.

I'm going to pickup the plumbing parts to just remove the 2 coolers, and loop the cooler lines together. I can run without oil and trans coolers to test
 
IMO, if the coolers don't leak (particularly if factory fittings, not so much if just hose clamps) I REALLy don't like removing them if not necessary. Fittings have a very nasty habit of leaking if they have been sealed for years and are suddenly freed then asked to seal again.

The oil lines on the later ones seem to be the real problem children. Mmight work ok, just my experiences with old hoses.
 
Man this is a long thread. I didn't exactly read every reply... but thought I'd share what I've got going in mine.

Aluminum/plastic stock replacement (tow package A/C blah whatever) radiator from Autozone. Seems thin.

Severe duty fan clutch (stock fan blade). It's big, and it takes a while for the fan to spin down in the morning. Like, until the t'stat pops. And when it starts to "lock up" you can hear the fan. I never tried it, but I bet it will pull a rag against the grille. Probably not when warm though (get to the warm part in a minute)

195 degree stock replacement t'stat.

Autozone/ Duralast "HD" water pump

12" electric fan on the "cold" side of the radiator.

Usually, I'll see what seems to be 190 on the dash gauge. My rig is missing the factory oil cooler (not my choice) but the A/C condenser is there (although inop). I'll use the electric fan (selectable) off-road, slow going uphill, or just whenever the gauge starts to get close to 210. Prior to the electric fan, I'd see as high as 220 (guessing, it was over 210) when it was over 100 out and we were loaded for camping, slow going (25 mph or slower) uphill.

An option that I have used in the past was a high flow t'stat. I think Robertshaw makes it; it was rated at 195 degrees, but I would see it open and close once I put in the aluminum radiator. It was basically flowing so much that the engine would get cold!

I wish you luck, I know these things are difficult to deal with.

Clay
 
Thanks for the response. Any more info on your 12" electric fan?

Where is it? Oil cooler spot?

Also, any more info on these high flow tstats? That sounds awesome . Would allow it to cool better, but still warm up.
 
It's hard to find the thermostat; I found one at Autozone which was correct but here's a link to Flow Kooler's site:
http://www.flowkoolerwaterpumps.com....html?osCsid=85ccd2aca47ec4f75c193e43c4a139f6
The opening is really big, just like that diagram. I see that Autozone lists some Mr. Gasket stuff now that doesn't look the same. When it opens, you see the temp needle drop, and I never had any heat issues during the summer with that in there. Had to pull it out for the winter though, especially since putting in the aluminum radiator.

I believe this is the fan I used:
http://www.jegs.com/i/JEGS+Performance+Products/555/52131/10002/-1
But since I never had the oil cooler (PO work) I'm not sure which side of the radiator it was located; I mounted the fan to the passenger side. It fills that area of the core support nicely. I also ordered the relay kit for the fan, and just wired it direct to a switch I have inside. I am not sure if I want to use a thermostat switch for the fan yet, since I watch the temps I am on top of kicking it on anyway.

Clay
 
It used to be that the Robertshaw stuff was good, I've heard that with pretty much all other aftermarket thermostats, their quality dropped.

FWIW, you shouldn't see temperature swings if a thermostat is working properly.
 
dyeager535 said:
It used to be that the Robertshaw stuff was good, I've heard that with pretty much all other aftermarket thermostats, their quality dropped.

FWIW, you shouldn't see temperature swings if a thermostat is working properly.
Click to expand...

I have seen certain vehicles have the temp swings (t stat open, and cant shut quick enough, so coolant temp gets slightly below stat temp, over.. and over) usually on vehicles with very good cooling systems.

Some of the mid-late 90s 6.5s use a high-flow style t stat, that will work in these motors (usually 180 deg though) that the dealership will have in stock.
 
black dawg said:
I have seen certain vehicles have the temp swings (t stat open, and cant shut quick enough, so coolant temp gets slightly below stat temp, over.. and over) usually on vehicles with very good cooling systems.

Some of the mid-late 90s 6.5s use a high-flow style t stat, that will work in these motors (usually 180 deg though) that the dealership will have in stock.
Click to expand...

I believe that was the case with my situation, the t'stat could not close fast enough once the cold water hit it. The high flow t'stat worked great with the stock brass radiator, but once I got the aluminum one installed I started seeing the swings in temp. It did settle after a while on long trips, but not on a 20 minute commute to work in mid 30's to mid 40 degree weather.
 
Really curious to see how the high flow behaves in mine. We shall see.

Thanks for the continued help everyone!
 
Got a high flow Tstat from clay today. Thanks man! Installed it, will see how it does tmr!
 
So, high flow is in. Opens a bit slow (like EVERY tstat in this truck), but seems to work fine otherwise.

Truck runs a hair over 210, but i couldn't get it to climb from there.

Interesting to me how the temp spikes before the tstat opens on each different tstat i've had. Thinking that may be the key to my issue.

That being said, i think the high flow is a good bandaid for the time being.
 
IME spiking was caused by low coolant levels.

I'm flummoxed as to why they would spike in your case, especially all of them. I see some temp variation in mine, but only from rated temp as it climbs when I'm pushing the motor pretty hard at lower vehicle speeds. However the temp climb is linear and expected.
 
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