CJ-7 Still Running Hot... Help Please!

[Jim_Lou]

Very little, but the heater core is just a small radiator, so if anything it will make your over-heating a whisker worse. There's no way it could help.

Have you done any sort of test to look for a combustion gas leak? There are analyzers that can detect combustion gasses in the coolant. Any well-equipped shop should have one.

[Caver Dave]

Originally Posted by kirk211

What are your thoughts on taking out the heater core and bypassing it? Will it make any difference in cooling?

Unless your heater core is plugged up, you'll likely see an increase in temps. IOW, the heater core (working by your admission) is ALSO dissipating heat just like the rad.

One trick I've seen of is stacking washers under the cowl side of the hood hinges to create a 1" gap for the underhood heat to escape through. You may want to pull the hood completely for testing, even though it doesn't appear to be the overall cause.

I know a couple guys that ran 350 Buicks (in Jeepsters) and ALL fought the heat monster. The one I'm most familiar with threw $$ at it (remember Scotty "BumbleBee" Rich? ) like he was tired of burning it! Huge racing AL rad, Postal grill, Hi-flow water pump, different shrouds, multiple electric fans, reg. AF + water wetter, special ("waterless") coolant, ultra tuning (timing/carb), dozens (if not hundreds) of hood louvers @ $5/ea and months of diagnosis... I honestly think he sold out before finding the cause!

[380tom]

Not to Hi-Jack but....I am having the same problem with my Jeep running the Buick 350. Although it does not get hotter while I'm driving just at idle. As long as I'm moving it's ok but as soon as I stop or am going really slow the temp guage just keeps climbing until I have to shut it down.

I am running a 4Core radiator, dual electric fans, 190 t-stat, royal purple additive (supposed to make it run cooler) and still no change. I have not checked the water pump to see if it should turn clockwise or counter but that doesn't seem right to me (I'm not questioning the fact that yours does but maybe they built the one you have wrong) I have the owners manual and it shows how the belt should run. It shows nothing about a double V belt or the waterpump running counter clockwise.
All that being said I have done alot of research on these Buick 350's and it seems to be a trend that some have issues with overheating and some do not. The million dollar question is WHY!!!! Nobody can seem to come up with an answer. I have a buddy running the exact same setup I have and he runs at 185 degrees all day long highway or idle no problems. The only difference is my motor has 200 miles on it and his has 150,000 miles.
I hope to see a resolution to your overheating issue. It seems weird that it overheats at highway speeds though you would think it would run cooler due to the mass airflow????
I will keep watching this post to see if you do find an answer and if I come accross anything in my overheating adventures I will definatly post it here for you. Good Luck!

[Caver Dave]

Originally Posted by Caver Dave

The one I'm most familiar with threw $$ at it (remember Scotty "BumbleBee" Rich? ) like he was tired of burning it! Huge racing AL rad, Postal grill, Hi-flow water pump, different shrouds, multiple electric fans, reg. AF + water wetter, special ("waterless") coolant, ultra tuning (timing/carb), dozens (if not hundreds) of hood louvers @ $5/ea and months of diagnosis... I honestly think he sold out before finding the cause!

Originally Posted by 380tom

The only difference is my motor has 200 miles on it

Scotty's was a fresh rebuild also... hmmm?

[RRich]

Somewhere I read, or heard - long ago, there are 2 different head gaskets that fit the Buicks - maybe even more. As I remember it was a problem even with T bucket Roadsters with the engine out in the open - obviously not an airflow problem. Seems like I ran into it years ago with aluminum heads on the cast iron block - a customer's roadster.

One gasket set doesn't have the cooling holes in the right places, or they are blocked off. I really don't remember why there are two configurations - maybe different years? Mismatching the heads and the blocks, or even just the wrong gaskets themselves create the problem. The cooling casting holes must match up.
Or I wonder, are the heads really identical side for side? We get used to putting heads on either side, but -???

The same or similar problem exists with putting a 4.0 head on a 4.2. Some cooling holes are blocked (some even leak to the outside world,) unless the right gasket is found. I just went through that a couple of months ago - there are several that look like they'd fit, but --.

I'd use the laser thermometer - use it on the block right near the head gasket line, above and below the gasket. It might give a clue as to what's going on - without pulling the head off. If the head is considerably hotter than the block just below it - I'd suspect coolant isn't flowing between them, or not enough of it.

From the description, the radiator is cooling fine, the temps are low and it's dissipating the heat, - that wouldn't happen if the airflow is restricted. But the coolant in the block/head is remaining hot.

Except for Serp belts, I've never seen a V-belt's backside used. It would not grip properly.

Something you might try - if the heads have a freeze plug on the back of them, remove it, then use pressure to force water from the front through the block - it should make a flood out the head's freeze plug if it's open.

Easy way to access those freeze plugs, cut a hole saw hole from inside through the firewall.

Jim Serr - founder of the American Jeepster Club had a custom radiator made - the upper and lower were divided into halves (crossflow.) Coolant flowed through the upper half, then dropped down through the lower half, almost like it was 2 separate radiators. I don't see the advantage of it, but he said it cured his overheating - a shop recommended and custom built it for him.

[CJ7Taz]

Originally Posted by 380tom

I have not checked the water pump to see if it should turn clockwise or counter but that doesn't seem right to me (I'm not questioning the fact that yours does but maybe they built the one you have wrong) I have the owners manual and it shows how the belt should run. It shows nothing about a double V belt or the waterpump running counter clockwise.

No, they didn’t build his wrong. If his pump runs backwards it is for use with a serpentine belt. Either his engine originally had the serpentine belt and was converted to v-belt or somewhere along the line the wrong water pump was installed.

When converting from serpentine to v-belt, the water pump must be replaced with one of correct rotation.

[RRich]

It certainly makes sense that there are two "flavors" of them - V and Serp.
I'd check with a different parts house so as not to make the same mistake twice (their computer may be wrong.) A real parts house, not a discount house. Look at several NEW ones older and newer than the one you have.

Parts houses tend to combine numbers to streamline inventory without realizing they are getting things mixed up.

And - "rebuilders" aren't the best at keeping things right. They mix and match parts and mislabel boxes. I've seen how some "rebuilders" do things - that's why whenever possible I select new.

[LEVE]

If it ain't what it is.. it's what it ain't. Did anyone check the exhaust to see if it's trapping heat in the engine?

[IN2DEEP]

Have you tried to find you another forum to post these questions? Maybe it's a common problem with these engines, and unless you've dealt with them more than once, you wouldn't know what to do about it. Plus, maybe they have a quick and easy answer to your overheating....... it's worth a shot....

[lojones]

You have a trans temp gauge? If not have you tried switching to an external trans cooler? I switched to a B&M plate cooler in front of the radiator and dropped a few degrees, but my th400 was getting worn out and running hot.