Temp rises when stopped

I bought a 1990 XJ awhile back. It got icy two weeks ago so I was using it to get to town and back.

I noticed that the heater was not as warm as normal and on the penultimate drive, it wasn't getting warm at all. On the last drive, at 28 degrees F outside, I went about three miles and happened to look at the temp gauge and saw it rising. I was on an icy downhill road with no shoulder and couldn't pull over. At the bottom, I just pulled over and the temp gauge was at its zenith, steam was coming out, and the engine shut off.

I raised the hood and saw a small amount of antifreeze at a couple of spots but the steam subsided quickly and the engine and hood didn't really feel that hot. (I didn't touch the engine directly; just put my hand barely above it.)

I had it towed to my friend's shop because the roads weren't icy along that route. He found that it didn't have a thermostat at all and thought it was low on anitfreeze to begin with. I also noticed when I bought the jeep that there was no covering above the fan. (I've later learned here that it is called a shroud and I picked one up yesterday.)

Questions:
1.) Why would the previous owners remove the shroud and t-stat and not replace them.
2.) There is also something missing directly in front of the radiator as I can see hoses that don't connect to anything. It looks like something to do with AC. Is it harmful to the system not to have this item?
3.) I driven this home from the shop (about 5 miles) and the temp gauge reached a point where it moved up a bit. Then, at a stop sign, it rose to just under the red marks. Is this expected?
4.) The temp gauge went higher after shutting off the engine. Is the gauge accurate when the engine is first shut down?

Thanks for the help.

By the way, it heats up real good now so the heater functionality seems to be working fine.

The shroud is easy to break (accidently leaning on it when checking oil), and in many climates not very essential (if it gets really warm than the shroud maybe important, I don't know since it never gets that warm here; my xj doesn't have a shroud and cools fine).

Driving without t-stat is not good. Engine stays cool too long. Put one in. However, it seems that yours is getting way too hot (close to red right?) which indicates that your cooling system is not ok. Maybe flush it through to make sure the coolant flow is uninterupted.

Not sure if the gauge is accurate after shutting down the engine but it makes sense to me that the temp rises a little. After all, the cooling circulation and radiator air flow is stopped but there is still a lot of heat in the engine block that will cause further heating of the coolant. Just my 0.02.

Thanks for the reply. I forgot to mention that my friend did install a t-stat and I assume that is why the heater began working so well.

I'm thinking about buying a new radiator and trying to install it myself so I'll try flushing it out then. I'm a neophyte with auto repair but there is great instruction on this web site about how to perform these tasks.

I just got my Hayne's manual from Amazon. Are there any other manuals worth buying?

i would diffiniely do a coolant flush and check the cooling system. if your coolant has too much water in it, it can freeze and cause part of the system to be blocked. i had this happen to me. it froze in the heater core and would not let the coolant flow efficiently and created dead spots. also it fried my water pump.

since you know some screwy things were done to your heep, a good check is in order. make sure the hoses are all in good condition (heater hoses too) and preform a good flush to make sure there is no debris that made its way into your cooling system. then afte making sure you got all the water out from the flush, refill with proper water/antifreeze solution.

hth

furrymcmonst said:

I just got my Hayne's manual from Amazon. Are there any other manuals worth buying?

Click to expand...

Get the Chiltons manual or a FSM if you can, so much better than Haynes

What does FSM stand for? Where can you buy it? Amazon?

Anyone have an answer to question 2 from the original post?

Thanks for all of the help.

furrymcmonst said:

What does FSM stand for? Where can you buy it? Amazon?

Anyone have an answer to question 2 from the original post?

Thanks for all of the help.

Click to expand...

Factory Service Manual.

As for your question, I would guess that it's the AC condensor. You don't need it unless you want air conditioning

Can you only buy the FSM from the dealer or is it at all the big bookstores, etc?

I got some time to kill so here goes. That AC thing you asked about in front of the radiator was the air conditioning systems condenser coil, it looks really similar to a radiator with cooling fins and all. My hunk of junk had multiple refrigerant leaks and the condenser was falling apart. It was impeding the air flow though the radiator so I just cut the lines and pulled it out. Yeah this hurts the ac system because of the moister that getting in there but it didn’t work anyway and I didn’t have the $ to fix it right. If yours hasn’t been in scents you got it, yours doesn’t work either, it least it’s out of the way of the radiator. As for as the environment goes….if it was going to be hurt by the refrigerant at all…the damage has already been done and your not hurting anything by leaving it open now.

It’s good you have a t-stat now, sometimes peeps take a faulty t-stat out if the vehicle over heats but that should be temp fix just to get home. Besides staying cold too long, if it is run for longer periods of time it can cause it to over heat because the coolant isn’t staying in the radiator long enough to cool down. The hot water goes back into the engine and gets even hotter.

It looks like everyone pretty much covered every thing you should check but I’ll add this. Before you buy a new radiator get a manual and a flush kit from Auto Zone or whatever and flush the system. You don’t have to pull it to do that. Also check to see if the cooling fins are all bent over. The guy that left out the t-stat, shroud, and pulled the condenser. Sounds like the kind of guy that would have F’ed up the radiator while working on it. If the fins are bent you can get a thing that looks like a metal comb from the parts store to straiten them so the air can flow though.

Good luck and I hope you get it all sorted out. Johnny O.

Thanks, Johnny O. I was worried that the missing condenser was somehow factoring into this. It's good to know that I don't need to worry about it.

Since this thing has 205K miles, it's probably due a new radiator. At only $150 or so, I may just get a new one since it's not that expensive. (Sounds good to say now but my Scottish heritage may overrule that when push comes to shove.)

If it overheats at an idle, the most common failure is the fan clutch, followed by a plugged radiator.

Also do a search on burping the cooling system.

furrymcmonst said:

Scottish heritage may overrule that when push comes to shove.)

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I always herd that Scotts had Deep pockets and short arms! :laugh:
Really tho you should try the flush first. Unless its just obviously all messed up when looking at it. like mine, any normal person would probably replace the one in my hunk (rusted frame, bent fins, missing fins, JB weld patches on holes….) but it holds coolant and don’t run hot so until then I’ll drive it like it is. (don’t judge me…it was free and I’ll give it away one day )

old_man said:

If it overheats at an idle, the most common failure is the fan clutch, followed by a plugged radiator.

Also do a search on burping the cooling system.

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x2.

I'd replace fan clutch.
Then wire elec fan to a switch.
then have rad checked for flow, if all checks out, have motor AND block BACKFLUSHED.
Make sure factory temp gauge is working properly.
(I didnt check your year) If open cooling system, buy a new 16 psi cap, good cheap insurance.

Start simple.. work your way up! Good luck!

When they overheat they are a beast to track down, but once you do, you'll be amazed at how cool she can run.

The xj i just sold wouldnt hit 195* beating on it in 90* weather

If I see the mechancial fan running when I start the engine, does that mean the fan clutch is okay? Is it an off-on kind of thing or does it spin at different speeds according to the temperature?

Its not the depth of the pockets, or the length of the arms, its just....wellllll......WE'RE CHEAP....lol.

try www.radiatorbarn.com It'll do your golf loving,Haggis eating heart good.
Good Luck from clan MacAllister

The fan clutch has a thermal function that will cause less slippage when it's hot. It always slips so you can't determine that it's okay just because it's turning. There's not a simple way to diagnose it other than by substitution.

By the way, it appears you have an above average vocabulary.

PaulJ, thanks for the answer on the fan clutch. I see you are in Lynnwood. I'm in Monroe which isn't too far from you.

As for the vocabulary, I read a lot and work around some fairly high IQ people in the software industry. I pick up a lot of new words from my boss! I tend to look up words I don't know in the dictionary instead of just blowing past them when reading.

Here's one for you: absquatulate. "Someone absquatulated with my t-stat and fan shroud!"

furrymcmonst said:

PaulJ, thanks for the answer on the fan clutch. I see you are in Lynnwood. I'm in Monroe which isn't too far from you.

As for the vocabulary, I read a lot and work around some fairly high IQ people in the software industry. I pick up a lot of new words from my boss! I tend to look up words I don't know in the dictionary instead of just blowing past them when reading.

Here's one for you: absquatulate. "Someone absquatulated with my t-stat and fan shroud!"

Click to expand...

Haven't heard that one in a while - I usually apply it to myself "I performed a rapid four-legged absquatulation with xxx."

I do enjoy seeing odd words - I've always been fond of archaics.

Oh - my first guess is also a fan clutch - they seem to last about four years anyhow. A viscous clutch isn't an "on/off" deal like you're probably thinking of tho - it's more like an "allowed slip" sort of thing. As they fail, they allow more slip.

When you are travelling forward, you have ram air over the radiator, so mechanical fan slippage is less of a problem. When sitting still, you don't have "ram air," so you need more from the mechanical fan. Since you're not getting it, you're overheating at lights.

Try this - get up to temp and idle somewhere, watch the gage start to climb. When you notice this, run your idle up to 1200-1500rpm - you should note a decrease. This is going to check your radiator circulation and your fan clutch (if it doesn't start dropping, you've got more trouble than just a fan clutch. If it's just the clutch, you'll see it drop because the "allowed slip" is going to take the same percentage out of a higher speed - so the fan will still turn faster.)

Also note that the effective service life of the OEM RENIX radiator runs 150-180Kmiles - after which, you should just replace the thing. Go aftermarket - I like Modine, and there are numerous favourable reports from the field on the CSF from DPG Off-Road - who is also a sponsor. Pity I didn't know about him earlier...