Topic: xj 4.0 overheating (Read 4676 times)

just-boot-it! · « **on:** October 01, 2011, 05:11:08 PM »

Help! My 4.0 xj keeps getting all hot and bothered! The temp guage has sat at one notch above normal since the hot weather has come,but once before I got home and it boiled over and it had a wee on the drive. But tonight when I got home the temp guage went mad. It sat at idle while I opened the gates and when I got in the car the check guages illumination light came on then the temp guage went to 3/4 or the start of red. Im not sure if the rad is blocked, the water pump is knackered?? I know the straight 6 engine is a brute but should it run hot all the time?
Help please!!

bigjeepzj · « **Reply #1 on:** October 01, 2011, 05:17:13 PM »

is your electric fan cutting in ?

just-boot-it! · « **Reply #2 on:** October 01, 2011, 05:45:24 PM »

yes mate it runs alot of the time. The A/C dosent work if this has anything to do with it?

big g · « **Reply #3 on:** October 01, 2011, 05:50:45 PM »

Rumour has it the I6 is partial to lunching the waterpump around 130k mark.

Have you tried backflushing the system?

Mike Pavelin · « **Reply #4 on:** October 01, 2011, 05:51:29 PM »

Is the viscous coupling any good?

just-boot-it! · « **Reply #5 on:** October 01, 2011, 06:28:45 PM »

Its got 113k and the pump does not leak but it could be that. I havent tried flushing the system yet, and help me out on the viscous coupling, the viscous fan works ok.

bigjeepzj · « **Reply #6 on:** October 02, 2011, 10:59:43 AM »

the pumps have been known fail so the impeller is not attached to the shalf and so the pully spins but the impeller stays still.
the only way to check it is to remove it an have a look

just-boot-it! · « **Reply #7 on:** October 02, 2011, 11:11:21 AM »

Thanks for the info, ive been out for an hour this morning on and off road and it hasnt overheated but the air temp was around 20'c where as last night it was nearer 30'c. I think the pump shall have to come off for a butchers.

bigjeepzj · « **Reply #8 on:** October 02, 2011, 12:13:11 PM »

there's also this you can try

http://www.go.jeep-xj.info/HowtoRadiatorRestrictor.htm

just-boot-it! · « **Reply #9 on:** October 19, 2011, 06:39:02 PM »

Took the old pump off today and it seems the fins have worn away, as you can see from the pics of the new and old pump pics. I will fit the new pump soon as the one i bought had a machining fault as the top pipe wouldnt screw on. Hope this helps people with the same symtoms.

Dave69 · « **Reply #10 on:** October 19, 2011, 09:31:57 PM »

never had a heating issue but did have a failed seal which was leaking so replaced the seal and pump in one hit and found mine to be in the same condition. the confusing bit was that there was no play in the impellar to shaft fitment . so the wear on the housing even tho' evident was a bit of a mystery

bigjeepzj · « **Reply #11 on:** October 19, 2011, 09:43:28 PM »

it's water erosion or cavitation

http://en.wikipedia.org/wiki/Cavitation

just-boot-it! · « **Reply #12 on:** October 23, 2011, 05:48:24 PM »

Finally fitted the new pump, get the blue print one, £75 ish if you can from the factors as it is better quality than the 50 qidder, also fitted a new stat, flushed the rad and bled the system with the rad cap off, it now heats up and when the ac is used or the engine gets hot (105 ish) the electric fan kicks in and brings it down under 100. Also replaced the bottom rad spring clip with a jubilee as the spring type are shite!! Hopefully its sorted now.

John McBride · « **Reply #13 on:** October 25, 2011, 06:41:29 PM »

I fitted the Hesco pump that has a billet machined impeller. This is far more efficient than the standard tin impeller and vastly reduces cavitation. This is also meant to cure the hotter running cylinder #1 caused by cavitation. Although ive no way in looking in to see whats taking place, i can say that that low speed low revs high load heat issues dissapeard. www.hesco.us

Dave69 · « **Reply #14 on:** October 25, 2011, 06:55:55 PM »

the spring type do what they are designed for and allow the pipe and hose to expand and contract when the cooling system expands and contracts with temperature. Jubilee clips work well as the dont leak when tightened onto a cold system. The downside is that when the system gets hot the clip doesn't expand causing the hose pipe to get unduly compressed causing the hose pipe (o.e) to develop cracks later on and not return back to a smooth shape when the clip is removed.

just-boot-it! · « **Reply #15 on:** October 27, 2011, 06:44:36 PM »

Thats fair enought but it has leaked ever since I bought the vehicle. Surely if it looses its tension over the years it will start to leak? Every time you unseat rubber hoses it takes a few times of heating up and cooling down to reseat itself as I have found out.

Dave69 · « **Reply #16 on:** October 27, 2011, 09:18:48 PM »

just a piece of useless trivia

just-boot-it! · « **Reply #17 on:** November 20, 2011, 06:41:49 PM »

Im now starting to get pissed off

. Having had the new water pump fitted for a month or so the temp runs fine around town, mostly just above idle 30 mph ish the fan kicks in just after the temp needle goes above halfway and brings it down again but on the way to derbyshire today when running around 50 mph then onto the hilly A roads around 2k revs the temp guage went to 1 notch above half for 10 mins then the check guages light comes on.
Is it time to fit a new rad, as it has a new pump and thermostsat so is it this the way to go?
I havent seen many posts on here about this problem but god is it annoying, so peeps any ideas??

Dave69 · « **Reply #18 on:** November 20, 2011, 07:09:18 PM »

is the temperature gauge reading correct?

can you put a thermocouple in at the top hose and monitor the temperature from there?

just-boot-it! · « **Reply #19 on:** November 20, 2011, 07:19:05 PM »

I believe the temp guage is fine as you can hear the electric fan kick in it falls slowly, and before the pump was fitted and it boiled out the expansion tank when the check guage light was iluminated the needle went upto red. After I managed to get home ( was about 5 mile from matlock ) I went out round the green lanes near me and there was no problem as I was crawling at tickover and the electric fan kept it cool. Pain in the arse as I cant go further than 10 miles from home

Dave69 · « **Reply #20 on:** November 23, 2011, 01:34:36 PM »

normally when your crawling around the temperature is high due to the lack of flow through the radiator so your then relying on the cooling fan to do the job.
It's odd that when your moving at road speed the air through the radiator isn't sufficient to cool the jeep. Although you have fitted a new pump did you fit this yourself or used a garage? If yourself i assume you checked the feel of rotation before the aux belt was refitted.

Going by this i would take a stab that you might have a restriction in the water circuit which is not allowing the water to flow at the pump speed defined by the engine rpm, which then results in overheating as the water isn't passing through the radiator quickly enough to dissipate the heat

just-boot-it! · « **Reply #21 on:** November 23, 2011, 06:54:40 PM »

I dont mind abit of spannering but a mechanic friend helped me fit the water pump, which stopped the overheating at low speed/low rpm but as you can see from the pics the rad was slightly poorly. The same friend pressure tested the rad as it is a 16 psi radcap but at 7 psi it was having a wee on his workshop floor and it was full of rad weld etc. Aaaah the saga continues![attachment=2]

big g · « **Reply #22 on:** November 23, 2011, 07:05:59 PM »

just-boot-it! · « **Reply #23 on:** November 23, 2011, 07:14:17 PM »

thanks for the motivation !

Dave69 · « **Reply #24 on:** November 24, 2011, 09:36:39 PM »

is/was this the rad you have currently fitted post pump change?

if so with those figures and the way it looks this might be your problem as those fin holes look quite restricted.

do you have a new rad fitted?

Author Topic: xj 4.0 overheating (Read 4676 times)

just-boot-it!

just-boot-it!

big g

Mike Pavelin

just-boot-it!

just-boot-it!

just-boot-it!

just-boot-it!

John McBride

just-boot-it!

just-boot-it!

just-boot-it!

just-boot-it!

big g

just-boot-it!