Topic: Do i need a new radiator?

[stan98tj]

Been noticing the Jeep running a bit warmer than usual. Today however, I watched the temp spike up quite a bit while I was at a traffic light. Once I got moving to about 50mph, it dropped back down.  But it seems to hover exactly at 210 when at slow speeds, and drops if I go faster. I got home threw it in park and waited. Nothing moved for a min or two. I put it in drive and stood on the brake and after about a min, it steadily started climbing. I've not seen this happen before and I wonder if it will pose an issue on the trail. I don't want to be wheeling and have it overheat given the strains on the motor and the low speed.

[Jeffy]

What's it usually run at?  Do you have a separate transmission cooler?  How's your clutch fan?

[stan98tj]

What's it usually run at?  Do you have a separate transmission cooler?  How's your clutch fan?

Usually runs at below 210.
Auto tranny. Though the tranny lines run through the bottom of the radiator.

[neale_rs]

x2 on checking the fan clutch.

My YJ usually runs a little hotter on the highway and cools down at slow speeds.

[Jeffy]

210 is about normal running temp for the engine.  The thermostat opens at 195.  I'm wondering if your clutch fan is slipping.  Try spinning it by hand.  It should not free spin but rather you'll get maybe 1/4 turn out of it.

[sharpxmen]

i say also fan clutch first, unless your coolant looks muddy (which might mean some of the radiator cells could be plugged) it's probably not the rad but worth checking that also).

[stan98tj]

So basically try and free spin the fan, it shouldn't spin all the way...
I'll check it tomorrow. Why wouldn't you guys think the rad is to blame? Also, is it possible for the rad to be clogged or dirty? THis seems to be the original rad.

[Jeffy]

So basically try and free spin the fan, it shouldn't spin all the way...
I'll check it tomorrow. Why wouldn't you guys think the rad is to blame? Also, is it possible for the rad to be clogged or dirty? THis seems to be the original rad.

Because it's cooling down when you're on the move.  When the Jeep is moving the fan doesn't really do anything.  It only comes into play at slow speeds.

[sharpxmen]

what he ^ said, but could be both (combination of the rad not flowing properly and the fan clutch)

[Jeffy]

what he ^ said, but could be both (combination of the rad not flowing properly and the fan clutch)

I think it would be more likely that his coolant is too weak or the radiator cap not working then the radiator though.  Stan, do you have a coolant tester?  Most people don't have a pressure tester but that's something to check as well.  Though you can usually see if the radiator is flowing if you remove the cap and watch as the thermostat opens up.  Some coolany will spill out as pressure builds and the thermostat is still closed.  Thought I'm thinking the clutch fan is the most likely.

[stan98tj]

Well, I tried to spin the fan and it provided the usual amount of resistance it usually does.. Turned about a 1/4 of a turn and stopped..

[sharpxmen]

hot or cold? when mine went bad was spinning more freely when warm, but i never seen it overheating even when that happened so maybe you're right about the rad - take the cap off and look at the core.
the other thing, do you have enough coolant in it, mine did that once and i was missing some, the moment i would rev it the temp would go back down.

[stan98tj]

hot or cold? when mine went bad was spinning more freely when warm, but i never seen it overheating even when that happened so maybe you're right about the rad - take the cap off and look at the core.
the other thing, do you have enough coolant in it, mine did that once and i was missing some, the moment i would rev it the temp would go back down.

I filled up the overfill bottle the other day. It was low. So it should have enough coolant.
I spun the fan when the engine was cold

[stan98tj]

So should I run the engine to temp, cut it and try and spin the fan? How loose is too loose? Should only get about a quarter turn, right? Also, would there be noise from the fan if it were blown?

[sharpxmen]

mine had noise
if it's bad you'll know, should spin at least a little less compared to when cold, it won't be solid but should tell you it's tightening when you try to move it.