new motor running at 210...do i worry??

just completely rebuilt my 4.0 in this 89 xj. runs great but at idle after a few minutes, the temperature rises to about 210 then the electric fan kicks on and cools it back to about 190.
ANy ideas???
New thermostat, full of coolant, new fan clutch.
Is this just how 4.0's normally run?

Jimminyc said:

just completely rebuilt my 4.0 in this 89 xj. runs great but at idle after a few minutes, the temperature rises to about 210 then the electric fan kicks on and cools it back to about 190.
ANy ideas???
New thermostat, full of coolant, new fan clutch.
Is this just how 4.0's normally run?

Click to expand...

That sounds pretty normal to me. Stock thermostat should be around a 192 degrees, so you shouldn't expect it to ever go colder than that once it's warmed up.

That is exactly how it should run! But, how is the radiator? If it's stock, you need a new one, and you should convert over to the new style heating system, closed, open, whatever people want to call it.

mjma said:

That is exactly how it should run! But, how is the radiator? If it's stock, you need a new one, and you should convert over to the new style heating system, closed, open, whatever people want to call it.

Click to expand...

Please explain why he needs a new one? And convert to what ? Open ? Closed ? Why ?
Do you even know what your talking about ?

To answer your question Jimmyc It's doing what it suppose to do.

Nothing much to worry about... especially with a "brand new" motor... they will run hot a bit at first during break-in, until things loosen up and the clearances aren't so tight.

One thing to think about though, especially with an older XJ, is how old the radiator is. I just replaced the "stock" (I assume, since I was only the 2nd owner and the 1st didn't have any receipts for radiator replacement) radiator on my '87 and it made a WORLD of difference in cooling... no more temperature swings... it just runs at a bit under the 210 mark ALL the time.

mingo said:

Please explain why he needs a new one? And convert to what ? Open ? Closed ? Why ?
Do you even know what your talking about ?

To answer your question Jimmyc It's doing what it suppose to do.

Click to expand...

Yes, that is where it should run.

As for the new radiator question. You could convert the closed system of a 89' to an open style of lets say a 92'. And the benefits of that are you ask? You can get rid of the unreliable pressure bottle, the PITA portion of bleeding the air out of the system and now you have a radiator cap that makes it easy to add coolant.

Parts needed:
92' Cherokee radiator (bolts right in) The one I got had a bung in it for the temp sensor for the electric fan. But never used it, I already had mine wired with a switch.
92' Heater control valve (replaces the old one)
Generic over flow bottle (got one at AZ)
6' of tube for the over flow bottle.
You will also need some heater hose of various lengths and sizes. Not much though.

All in all the only reason I did the conversion is because the old radiator died and I split 2 pressure bottles.

If you do a search you will find more detail than I gave here.

______________________________________________________
90' Xj Re 5.5", 4.88's, Detroit locked Dana 44 rear, rolling on 35" Xterrains with lots of trimming.

Visit us at www.pa-wheeling.com A site that has a lot to offer.

personally i would run a new radiator to compliment the new motor. if your not sure when or if it's ever been replaced, then most likely it's been in there long enough to build up tons of crud and isn't working quite as efficient anymore. and if you do decide to put one in, then i would do some searching on the forums/internet on converting to the new style "open" cooling system.

thanks for the input. i flushed the radiator when it was out so i dont think its working improperly. but i guess some of the lines could be clogged. i just noticed that going down the road it sits at 185 or so and then after it idles, it creeps its way up to 210. it was enough for me to ask for some opinions.

mingo said:

Please explain why he needs a new one? And convert to what ? Open ? Closed ? Why ?
Do you even know what your talking about ?

To answer your question Jimmyc It's doing what it suppose to do.

Click to expand...

Thanks for being pleasant!! :sunshine:

If you read what I typed, you would notice that 1)I had already told him that it is doing what it is supposed to do and 2) I had said that if he still had the stock radiator from 89, he should replace it now. Why put a good motor in with a radiator that is sure to fail soon? It is common knowledge that the stock radiators weren't that good. Then there is the pressure bottle cooling system which is a PITA. By definition, it is a "closed system" but for some reason it is commonly referred to as an "open system." Either way, if you're getting a new radiator it makes sense to go over to the newer style system. I used to have an 89 MJ and did the conversion when my radiator went, and I never had any more problems with the temp getting too high, which isn't good for anything under the hood.

So mongo, I think the question here is do YOU know what YOU are talking about??