please help save my new engine

I have a 97 XJ that I have just put a new engine in. The old engine had 226,000 miles and a valve went bad because of a sudden overheating problem. I thought the problem was just the old engine. First I covered all of the basic trouble shooting problems. New radiator, flushed the dashboard heating coils, no fail thermostate, new 16lbs cap, all new hoses, new gasket, and the last thing I have done is replace the fan clutch with a heavier duty one. The eletric fan is working and pretty much stays on all the time due to the higher temp. I have a dummy light on the dash so I can't see the actual temp the jeep is running at but I am going to install an aftermarket one asap. It is still overheating and flushing the coolent out of the reservoir. I have noticed that it is only at higher speeds (over 65 mph) that the problem is the worst. I have run out of ideas. please help.

Check the lower radiator hose to see if it has a coil spring inside it, running as close to the full length of the hose as possible. The lower hose is the suction hose, and if that spring isn't there (and it often isn't with aftermarket hoses) the suction at highway speeds can close the hose and cause overheating.

the new lower hose dosen't have a coil inside like you say but I have checked it's rigidity and don't think that is the problem. the old hose did have the spring and the problem was still happening. any other thoughts?

Maybe the t-stat is in backwards. Sometimes, the thermostat is a different design than the factory, and has to be installed backwards. I have had that happen a couple of times. It should be marked as to which side goes to the rad.

I agree with Eagle. Get a lower hose with a spring in it. Eventhough you say it is firm, once it heats up and gets suction it will probably colapse. If that doesn't solve the problem I would look to the t-stat. Try running without it and see if it still overheats. Other things to look at are the overflow bottle, to see if it has any small cracks, and the lid may not be sealing right. Also make sure that your coolant mix is 50/50. Good Luck!

First off try to find a gauge panel, you can use one off of a 97TJ in case you don't know that, thats what mine is off of. That might give you a better idea of whats happening. You don't have to change any senders either, it's a straight swap though you might have to move or add some lightbulbs around.

OK i got an aftermarket temp gauge installed. I just T'ed off the original and kept the dummy light as well as the aftermarket. I checked the lower radiator hose while the engine was under stress with it in gear and engine reving high. THe hose is not colapsing. I talked to a mech about the hose and he said that hoses are made much better now and the coils arn't in them because the quality of the hose is much better that in 97 and it shouldn't be colapsing. The thermostate is definitly in the right direction. ideling temp is about 225, eletric fan comes on at 210, and the overheat light comes on at 275. No crack in the overflow, but it is still flushing after driving and while driving. A friend told me it could be a cat converter with a broken loose core. He said the way to test it was to hold my hand over the tail pipe and rev the engine, he stated outward pressure would decrease while reving. This did not happen. I don't know if it is the cat con or not but I am quickly running out of money, time and ideas.

xtreemathlete said:

OK i got an aftermarket temp gauge installed. I just T'ed off the original and kept the dummy light as well as the aftermarket. I checked the lower radiator hose while the engine was under stress with it in gear and engine reving high. THe hose is not colapsing. I talked to a mech about the hose and he said that hoses are made much better now and the coils arn't in them because the quality of the hose is much better that in 97 and it shouldn't be colapsing. The thermostate is definitly in the right direction. ideling temp is about 225, eletric fan comes on at 210, and the overheat light comes on at 275. No crack in the overflow, but it is still flushing after driving and while driving. A friend told me it could be a cat converter with a broken loose core. He said the way to test it was to hold my hand over the tail pipe and rev the engine, he stated outward pressure would decrease while reving. This did not happen. I don't know if it is the cat con or not but I am quickly running out of money, time and ideas.

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I would still replace the lower hose with the coil inside the hose type. When your engine and cooling system is under load while driving it has more pressure on the system and could still be causing that hose to collapse and causing your problem. I would also consider looking into the cat. as being the problem. A friends ranger with a 2.9 v6 was doing the same thing after the rebuild except that at highway speeds he was ok. On trails rides, slow driving and at stop signs he would start to get hot. The reason I bring this up is that he never had the problem until his converter was clogged. It would break apart inside and loosen up sometimes and would run normal again but would happen again in a little while when the converter would clog again. I told him to replace the exhaust when putting in the rebuit engine but he kept the old. So he got a clogged converter and overheated his new engine a few times and killed it. There went $1200.00. Get that hose first and if that doesn't cure it I would look at the cat. next. Maybe even try another thermostat or boil the one you got and see if it opens and closes. Just an idea. Good luck.

Kim.

I have checked all of the autopart stores and no one carries the coil hose. Does anyone know where to get one?

xtreemathlete said:

I have checked all of the autopart stores and no one carries the coil hose. Does anyone know where to get one?

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From your local Jeep dealership.

Kim

i was told it could be an air pocket. Does anyone know how to get rid of an air pocket in the cooling system?

its a 97, so its an open cooling system, after its ran for a few minutes, there wont be any air pockets

Just some wild ideas:

1) Air flow through the radiator - maybe there's something blocking this in front of the radiator, maybe the A/C or tranny cooler is plugged with bugs..?

2) New motor has head gasket leak? There's a way to test for this. A radiator shop can do this.

3) Exhaust heat in the engine compartment? Maybe a broken exhaust manifold is venting heat onto the block. Not likely since you'd hear it.

4) You say the old motor died suddenly with an overheating problem. Sounds like the cat came apart since the cat is the same now as then.

5) Maybe it's running really lean?

6) I assume you installed a new water pump... If not then maybe there's a mechanical issue between pully and impeller.

7) Circulation through the motor as others have suggested: collapsed hose, thermostat upside down. Is there any other thing that might stop fluid movement?

8) Installed the fan blades on the clutch in the proper direction? It is marked with a 'front' side. Engine should roar and blow lots of air from the mechanical fan into the engine compartment when first started cold.

Somehow there's a reason it runs hot. At first I try to guess a problem and replace the proper part. But after a while it is just time to write a list of everything you can think of in order of probability or cost, then just start at the top. I've found it is cheaper most times to simply blindly replace things than it is to let the dealer fix. Sometimes it's not, but the times that it is make up for it.

Keep hunting and good luck!

Newer lower hoses have the coil spring molded in the rubber, it's there you just don't see it.

Make sure you have water flowing thru the sytem. One way to check is with the motor running, touch (grab) the upper hose going into the radiator close to the radiator , make sure it gets real hot. Also check the temp of the air being pulled out of the radiator by the fan. Is it hot??? It should be. I had an intermittent therm that stuck sometimes.

langer1 said:

Newer lower hoses have the coil spring molded in the rubber, it's there you just don't see it.

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Ummm, thats not always true, I've seen a lot of new aftermarket ones that dont. Just get one from the dealer, its not that expensive and you wont have to worry about it for a while.

Littlewhitexj said:

its a 97, so its an open cooling system, after its ran for a few minutes, there wont be any air pockets

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Thats not true. I've seen a lot of '91+ 4.0ls, mine included, that took a little work to get all the air out of it. Its always a good idea to burp the system whether its an open or closed system. The OEM thermostats with the burp hole help release trapped air too.

Today I am replacing the radiator again. It is under warrenty so I can get a new one for free just to iliminate that aspect. The fan is pulling air towards the engine, the upper and lower hose is very hot and full of pressure. The lower hose definitly does not have a coil and all dealers in the state have them on back order. I would like to replace it but still don't think it is colapsing. What is the porpouse of the radiator in the front? The transmision hose coming off of the radiator kinked when I was taking off the radiator so I will have to replace that. Where do I replace the transmission fluid? And is transmission fluid run through the radiator to cool it off as well? Deeper and deeper still without finding the answer.

The exhust manifold on the old engine was cracked but the new one is OK, the air flow isn't blocked through the radiator, I just took it off and checked, and there is 150 lbs of compression in all valves so I beleive the head gasket is fine, as well as the engine has plenty of power.

what is running really lean mean?