Overheating
 

Hey guys, I really need some help. My 455 is running to hot, or at least I think so. I live in Lower Alabama and the temp in the summer is always over 90 degees. It runs on the open road fine but when I get into traffic or turn on my a/c the temp goes to 210 or above. I have an aluminum 2 row radiatior (each row is 1") 2 puller electric fans, total of 2100 cfm, (fans are running in the right direction) I have an external trans cooler, 160 t-stat, the block has been decked to .010 out of the hole, heads are 6x8, water pump has cast impeller, timing is set at 16 base with light springs in dist. total at 2800 32. I don't loose any coolant, So I don't think it's a head gasket, it never misses. The temp guage is in the intake, not the head. There aren't any air pockets. Intake is stock 455 that has been deburred and stat housing separated and crossover cut and blocked in the head. I also had a 4 row stock brass and copper rad in it, before I went to the aluminum, with a 7 blade clutch fan and it ran hot with it. New clutch on fan. with shroud.

This is all I think of right now. If any of you have any questions before making suggestion just ask.

Thanks for all the great help I know I will get on this one.

Did you check to be sure the plate behind the water pump is in good shape and not full of holes and corrosion? There are also the two rubber seals that the plate pushes against for a seal. If they are bad, or not there, it won't pump enough water through the block. If all that is fine, you might look for a smaller water pump pulley if the one you have is roughly the same size as the crank pulley. This alone, drastically helped a friend of mines 455 out in the SW heat above 100°.

I was having issues with a new aluminum rad and a 160 t-stat in my car and it was running 215+.

I simply swapped to a 180 t-stat, and the thing runs right at 180. I think it has to do with it slowing down the water flow through the rad, giving it more time to cool.

You may have fan to shroud depth issues as with a shroud the fans blades should be half in and half out of the shroud. other wise the fan pulls in plenty of air, but it stacks up on the rear of the fan caused by the taper/restriction of the shroud.

wahts the coolant mixture?

I think 2100 cfm may be marginal to cool a 455 at low speeds and especially with the a/c running. I am in north central Florida, equally hot, and I had to go to a bigger electric fan to solve a hot running issue on my 79 T/A. I don't even have a/c but the original electric fans I tried wouldn't do the job; finally went to a Lincoln Mark VIII fan and car runs about 180 even on the hottest days. Not to say you might not have other issues but I would look at the fan situation for sure.

Electric fans
 

The fans, when mounted to the radiator only pull air through that area.= poor cooling.
Take or make a shroud that you mount the fans to, so it's back from the radiator.
This way air will get pulled through the entier unit.

Pontiac Gregg

I may be way off here, but I chased an overheating problem years ago and it ended up being the distributor vacuum advance leaked. This threw off the timing enough to cause the engine to run hot. Good luck! When women are hot,that's good, when your engines hot, that's not.........

I had a similar problem recently, I flushed the cooling system 5 times, then filled it with 70-30 mix (70 percent watter 30 percent A/F) and now I run 15 degrees cooler. SInce I don't have a separate tranny cooler, I put in new lines (the old ones were in bad shape) and slipped and insulator on the lines, they run right by the headers.
By the way I run a Taurus 3.8 fan at low speed with a 180 degree t-stat and a 175 degree fan switch.

Remedy for sitting in traffic TEMPS (this advice is good for ~2hours sitting, occasional creeping on blacktop roads in hot summer:

1: MECH fan (stock 7-blade) Flex-a-Lite stainless Stell 19".
2: Aluminum Water Pump
3: Hot-Idle lowered to a rationale 600-800RPM. (Q-Jet with Fuel Regulator)
4: Ignition Timing advance in the teens while in-gear. no higher, no lower.

If you cannot hold low idle in-gear with such normal timing advance, or cannot reduce the hot-idle to get that low, then go on a witch-hunt for the vacuum leak, or use leaky lifters to make you cam appear small. HIS

You need a 7 blade straight fan and that will fix it......

Thanks guys, I really do appreciate your suggestions. I am to the point that I will try anything to be able to run my Goat in the summer. I truly agree with 455Darren.

oh boy!!!!! that is a tuff choice ;)

Hey guys, I just thought I would give ya'll an update on the overheating problem. FIXED,FIXED,FIXED. I finally wound up putting the 7 blade clutch fan and shroud back on. Now it runs about 170 on the road with the air on and about 180/185 in traffic. Thanks for all the suggestions. You guys have more knowledge than can be put in any book.

That's good to hear - now get out there and enjoy that beautiful GTO.

Jim

Guys, IMO a 2 core radiator is insufficient in cooling that engine in traffic ESPECIALLY with a/c.

I would upgrade to a 3 or 4 core before anything else.

Then, Use the mechanical fan with a secondary electric pusher or puller if you have the space.

Correct me if I'm wrong, but I thought the aluminum radiators came in two wide rows and not 3 or 4 narrow rows. I believe that only copper/brass radiators have 3 and 4 rows. Every aluminum radiator I have had experience with were all two rows but as wide as a 4 row copper/brass radiator and they cooled better.

Correct. Two "long" rows will cool better than 3 or 4 "narrow" rows.

Correct on row identification. The very best aluminum radiators built at Mark 7 machine utilize two rows and they are 1 1/4 each therfore you receive a full 2 1/2 inch of tubes, this would compare to a 5 core copper/ brass unit. Check out the Mark 7's at : www.mark7machine.com (989) 922-7335. He also builds custom fan shrouds in raw aluminum or highly polished and or anodized in a rainbow of colors just like the custom radiators. There is a HUGE difference in cooling capabilities with those extra 1/4 inches per tube.

Tim john---

reread original post-- did not realize he had a modern al. radiator.

Then it becomes an issue of not enough air flow.

I had same problem, upgraded to electric wp and mark 8 fan, problem solved.