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cuemaker
07-17-2006, 10:04 PM
94 Jeep Cherokee 4.0L high output engine.

Friend just bought this used for a decent price.

After a 5min drive, the hood of the car was extremely hot. There isn't a protect heat covering on the underside like on newer cars.

The engine does not over heat and runs very very nice and smooth.

Is this a problem with the engine or does it just get that hot and without the protective heat shield under the hood the heat is transmitted through easier?

Thanks

Wareagle
07-17-2006, 10:53 PM
It is probably the lack of the insulation that is typically under the hood. As long as the engine isn't overheating, it should be a mechanical problem; the paint job might be another story!

You can buy insulation from aftermarket suppliers. You might try Summit Racing, Jegs, Speedway Motors, or any of the other parts houses for your application (if you need it). I'm sure there is several dedicated jeep outfitters that can fill the bill as well.

Refards, W/E

DancingBear
07-17-2006, 11:13 PM
Somehow I doubt the hood came from the factory without a heat shield. Which also leads me to wonder what might have happened to it. :eek:
If a replacement is available it sure sounds like a good idea.

Walt

EricS
07-17-2006, 11:52 PM
here is an idea
http://rbk3.com/fsj/hoodins.html

Which temp gauge are you using 'cause the factory gauges are mostly for entertainment value.

Eric

CCWKen
07-18-2006, 01:06 AM
Many autos since the early 90's have done away with the insulator. The newer paints can withstand a higher temperature and the lack of an insulator actually reduces the under hood temps. To be sure, check the under hood skeleton for holes. If someone took it off, you should see signs of where the push in retainers were removed.

cuemaker
07-18-2006, 08:45 AM
Thanks all. It was about my thinking too.

I was just concerned about the possibility of an engine getting to hot with out the thermostat saying its getting to hot.

The engine is smooth with very good pickup!

Evan
07-18-2006, 09:17 AM
Water temp gauges are a rough indicator of what is happening but if you want good information you need an oil temp gauge. The oil is an exact indicator of the temperature of all the parts that really matter and it's oil breakdown that kills an engine. I have an oil rad on my Ford Ranger with a valve body I made to bypass the rad in cold weather. I use a water temp gauge with a good high range to monitor oil temp. If you have a situation where the oil gets really hot then it is time to change the oil regardless of the mileage. This will help save the bearings. I put this on to help with towing my 5th wheel.

mjydrafter
07-18-2006, 10:01 AM
I'll preface by saying that I have a '92 cherokee. Exact same engine. Yes it did come from the factory with a insulation on the bottom of the hood. Mine has one. I would guess that you could fry an egg on my hood after some highway miles, with the insulation (the hood is also black which I'm sure doesn't help). The 4.0L likes to run at 195-210. If it has an actual temp guage or the dummy light the sensor is on the head next to the firewall & valve cover gasket. The sending units look the same but aren't just fyi, one wire to the guage and ground through the sensors brass body. The sensor up on the coolant neck is the sensor that the computer reads for engine management.

The 4.0L does not like to run below 195, it will stay in closed loop untill 170 (I think) and will run rich. It seems hot comparatively to other autos, but this range is where you want it. If it gets to 220 the aux/AC electric fan should kick on and the temp will go down, if it gets hotter than that, I would suspect the coolant sensor on the coolant neck not telling the computer to turn on the AC fan. The AC electric fan should run with the AC regardless of the engine temp.

Let me know if you have any other questions

jkilroy
07-18-2006, 11:51 AM
210 is not hot at all for newer cars. I believe the new vettes don't kick the electric fan on until 245.

LarryinLV
07-18-2006, 12:17 PM
195 degrees, 210 etc., that's just what the coolant temp is. Most of the heat transferred up to the hood is from the heads and the exhaust pipes. After a little time on the road those temps can be several times the temp of the coolant. And those little HO four bangers like to run higher revs and hotter temps to keep the power up.

Of course here in the desert the hood is too hot to touch just sitting in the driveway.

mjydrafter
07-18-2006, 02:10 PM
The cherokees engine compartments are a little cramped which doesn't help either. Not as bad as some, but my '79 f100, you could sit on the fender wells and work comfortably on most of the engine, (it had a merc straight six).

Some guys will put washers under the hinges on the hood to raise the rear end of the hood. Lot's of others use salvaged hood vents, off mid '90ish Pontiacs and older turbo LeBarron hood vents seem quite popular, for grafting into cherokee hoods. Some of the ones that are well done end up looking pretty nice. These are more for the hardcore guys that sit around idling forever winching or rock crawling.

I know that opening the hood on my cherokee w/o gloves when it's hot is just askin for it.

Fasttrack
07-18-2006, 07:29 PM
"Which temp gauge are you using 'cause the factory gauges are mostly for entertainment value."

hahaha - true! Another thing to consider gauge wise is an oil pressure gauge - i'm surprised that more autos today don't come equiped with one. Gives you a good indicator of whats going inside as well (not so much temperature wise, but it can indicate the conidtion of your bearings and valve train as well as allert you when pressure drops before you screw up anything).

wierdscience
07-18-2006, 07:41 PM
I'm going with insulation being gone,reason being I see a lot of them around town where the paint is gone on the hood,but nowhere else.

RobDee
07-18-2006, 10:38 PM
What color is the hood?

When I did large format film photography, remember that?, we did an experiment and found that a black cloth placed over a view camera was 25 F hotter then a white cloth.

I never buy black cars for a lot of reasons but that is certainly one of them!

Rob Dee

mjydrafter
07-19-2006, 08:29 AM
Black gets really hot, and it's hard to keep clean. In fact my hood has little blemishes all over it. They look like somebody with way too much time cut 3/8" razor lines in a random pattern all over the hood. I don't know enough about paint to know if it was some kind of contamination when the hood was painted or if it is the generous heat that radiates out. It's not really noticable untill you get right up to it.

When I got my Jeep it was between the one I got and a 1 year older and a little cheaper white one. I wanted the paint off the white one but the mechanical portions of the one I got, I guess that goes with buying used.

The only plus of black that I have ever heard is that it is easy to match...

operose
07-21-2006, 10:37 PM
Black gets really hot, and it's hard to keep clean. In fact my hood has little blemishes all over it. They look like somebody with way too much time cut 3/8" razor lines in a random pattern all over the hood. I don't know enough about paint to know if it was some kind of contamination when the hood was painted or if it is the generous heat that radiates out. It's not really noticable untill you get right up to it.

When I got my Jeep it was between the one I got and a 1 year older and a little cheaper white one. I wanted the paint off the white one but the mechanical portions of the one I got, I guess that goes with buying used.

The only plus of black that I have ever heard is that it is easy to match...


those 90's cherokees just had horrible paint...

I can't count how many I've seen driving around (including the one we had) where the clearcoat or whatever was peeling right off