Radiator/overheating questions

[ckhd]

Answer one or answer all!

Is Modine a good brand of radiator?

It seems that any new radiator I can find has the 'tube' style tranny cooler, is there a company that makes them with the 'plate' style like the one that originally came in my '72 'burb? (if so, does that company make a decent radiator?) A plate style tranny cooler is REQUIRED by bowtie overdrives to keep the tranny in warranty. My current plan is to buy a Modine and have the radiator shop pull out the tube cooler and put in a plate cooler.

I have changed the following: Water pump, fan clutch, and even tried a different radiator (a "ready rad" from checker/schucks/kragen), but my '72 'burb still overheats. The outside temp is in the 100 degree range. Any ideas on what to do at this point? Would a lean mixture cause it to overheat? (all this is at 65-70 mph and about 2000 rpm) Yes, I have a fan shroud and it pulls air through the radiator fine, and it's the stock '72 fan/fan clutch setup and stock short water pump setup, etc...

[Bill72BB]

I bought a Modine for my BB about a year ago at a local Radiator supply place ,no problems and it bolted right in I'm running a plate style tranny cooler .It was about 190 dollars.

I would install a 180 Degree thermostat and see if that helps also.

[tom hand]

What is your difinition of overheats? Is water boiling out of the radiator cap and hitting the ground or is the guage reading too hot for you?

[rickspickuppart]

I see your in Arizona also and our cooling problems here are alot different than most other states, if you have any questions about cooling problems call me at 1877 641-1387, we have seen and repaired about every crazy cooling thing you can imagine, I would be happy to try and answer any questions you might have.

Shawn

[cdowns]

modine is an excellent radiator, considering where you live i'd suggest using the rad trans cooler asis and adding an aux cooler in front of the radiator for additional protection for your tranny

[Longhorn Man]

9 times out of 10, any cooling problem while going down the highway is going to be a coolant flow problem rather than an air flow problem.
There are 2 things I would look at in your shoes;
!. The lower rad hose. While the truck is in neutral or park (and running @ normal temp), have someone hold the throttle at about 2800 RPM or what ever your cruise RPM happens to be. (if you have no tach, rev it till you think you're at cruise speed, then give it just a little more gas) While your assistant is doing this, you peer through from under the hood and look at your lower hose. Many older hoses required a coil spring in them to keep them from getting sucked shut at higher RPMs. If your hose looks like it is getting squished, get a new hose.
2. Your water pump is probably getting old and tired.

Those are the two normal things I see all the time at the shop for high speed cooling problems. There are other things to look at later, but like I said, one of these 2 items always seems to be at fault.

I also want to ask (like Tom Hand) what your definition of overheat is. If tye guage is running high and the coolant never pukes out, then get yourself an aftermarket guage and plug it into the engine...even if just to troubleshoot the engine. Onless your engine pukes all over the highway, I think this would be a wise first move.

[GreenMystChevy]

Wouldn't he mess up his engine before all the coolant spills to the pavement? What will give first, his engine or the radiator cap?
Just curious here too because I am having cooling problems and when it hits the "red-line" area on the temp gauge I shut her off quick.

[ckhd]

My definition of overheating: When the gauge hits the letter "H", or greenish-liquid boils, whichever comes first. In this case, it's the gauge hitting the "H", and when it gets hot, my tranny doesn't take too long to follow. I don't leave it running long enough to see if it boils...

Duh! I feel dumb, I haven't checked my lower radiator hose. Brain fart I guess.

I have a question about that... If the lower hose is collapsing, couldn't it also point to a radiator that isn't flowing enough coolant?

cdowns, I have a good aftermarket cooler (6" X 18" 12-row), but Bowtie Overdrives flat-out unconditionally must have a plate-style tranny cooler in the tank of the radiator in order to warranty their transmissions. They won't budge on it. My problem is that there aren't any radiator companies (that I can find) that put the plate-style in anymore.

I have talked to the local radiator shop. They will have my 'custom made' radiator by the middle of next week. Hopefully the only problem I have is that the radiator is 31 years old!

Shawn, if that doesn't do the trick, I'll give you a call!

[GasHog396]

I would like to suggest that you hook up a proper temperature gauge, at least temporarily, to get an accurate reading. The original gauge is 30+ years old now, and are probably off calibration in either the sending unit, or in the gauge, or both. The mechanical gauges are cheap (like $10 or so at Pep Boys or WalMart), and are suprisingly accurate. The biggest problem with them is finding a big enough hole in the firewall to pass the sending unit through. For a SB, I prefer to see no more than 20 degrees over the thermostat rating, and ideally, it should run right at the thermostat rating.

As for the lower radiator hose, it should have a coiled wire running through it to prevent water pump suction from collapsing the hose at higher RPMs. Sometimes the wire will work its way towards the pump, but more often, it just rusts away. Squeeze the hose in your hand (truck should be cold), and if it collapses, it's time for a new lower hose. (Note: try the upper hose first if you need to know how much pressure is required to collapse a hose without the wire.) The upper hose is under pressure from the pump, so it doesn't have the same problem, thus, no coiled wire. A lower hose without the coiled wire, even with a new radiator, will still collapse at higher RPMs.

The 180 degree thermostat is a good idea, but I wouldn't go any cooler, as unleaded gas needs the heat to burn correctly.

And finally, 'yes' running lean could definitely cause you to run hot. Running lean causes increased combustion tempatures and also leads to burnt exhaust valves and seats.

Good Luck!!

[ckhd]

Lower rad hose is fine. It does still have the spring (it's only about 3 month old). It's not even collapsing against the spring. I tried it hot and even up to 4000 rpm without collapsing.

I guess I do need to try a different gauge. How about an electrical instead of a mechanical? I hate those long springy sending units.

Any recommendations on brands? I know going from a cheap tranny temp gauge to a B&M, there were 30° difference between the two.

[Longhorn Man]

My 'cheap' sunpro tested 100% acurate in a pot of boiling water...but that is a mechanical.