Running hot

[yumpet]

my XJ is running hot again and i don't kno why the coolant is still good and the radiator has 't lost any fluid in the past few months, i don't know what too do now, i have replaced the thermostat, what next

also i want to look at putting some sort of vents in too cool it even more when it is in slow traffic (read as sand) as up here in the Isa my winter weather can be over 30 degrees, who has bonnet vents and what seems too work well, and yes i have seen go jeeps bonnet but i aint got the $$$$ to buy one

[Gojeep]

Did you look at all the other vent shots I have on another page there too? Also there is the write up on Davids XJ too.

http://go.jeep-xj.info/Vents%20017.jpg

[Glenn]

if you took that rubber seal out from the back edge of the bonnet and perhaps put a washer or two under the hinges to jack the rear of the bonnet a bit would that breath much air ?? cheaper and less nasty than digging holes in your bonnet maybe

[PK]

Grant has vents in his bonnet - maybe pm him.

Also check that your radiator isn't blocked - inside and out!

[DazzaXJ96]

Ouch that sound familiar. I have replaced the radiator, hoses, thermostat, coolant X 3, waterpump and it still runs hot in traffic or slow 4X4 driving. With the bypass switch I can now easily deal with those few occassions. Im still thinking to put in electric fan & bonnet vents but its no longer urgent.

[Gildo]

Replace your waterpump & thermpstat.
The waterpumps on these rust away quicker than your could believe because of the dissimilar metals.
My 98 had 180,000km and the impellors were completly gone. It was basicly a disc left spinning in the coolant.
The PO had replaced the rest of the cooling system and it was still too hot.
I have seen this in another 96 and a 94.

[xjdavid]

I had to replace the viscus fan at 130,000 ks. The XJs do run quiet hot and I have had mine with the needle at the end of the gauge and it didnt cause any real problems didnt even blow any water out. make sure the coolant mixture is actually 50 50 coolant and water as the XJ radiator not easy to drain and if the job is done at a shop I suppect that they dont take the time to do the job properly. The best ratio is 50 50. Apparently it is possible to get an after market aluminium radiator with larger tubes that will fix the problem. Not sure where to get them.

[Gojeep]

Actually tests prove that the more glycol you run, which is what most of your green coolant is, the worse it is. Water actually does a better job of heat transfer. The Jeep is designed to run with only a 1/3 mix to keep any freezing and corrosion at bay.

[Richo]

Ouch that sound familiar. I have replaced the radiator, hoses, thermostat, coolant X 3, waterpump and it still runs hot in traffic or slow 4X4 driving. With the bypass switch I can now easily deal with those few occassions. Im still thinking to put in electric fan & bonnet vents but its no longer urgent.

Dazza and Yumpet, you have both mentioned everything else but, have you replaced the clutch unit on the fan?? I think daykin and motorcraft both make one to suit.

the stocker does crap out over time, and you will find the fan is barely turning. Replace that, and it should fix the heating up in slow running problem.

And as Glen said, pack the bonnet with 4 washers per side under the hinges, will lift the rear of the bonnet 5-8mm, enough to let a lot of hot air out, and way cheaper and less hassle than vents.

[DazzaXJ96]

Hi Richo, yes I have thought to replace the viscus clutch on the fan however the cost (after-market $300+ from memory) was similar to buying an electric fan to fit myself. I have heard others say it fixed their heat issues however I like the 16" electric fan solution. Also I read here somewhere that putting washers on the hood will break the seal for the engine bay letting oil on the windscreen so its not allowed - or somthing like that. PS cheers gojeep my cooling system had a pin-hole leak not noticable in the expansion tank no more hot coolant smell.

[Gojeep]

Good to hear it is solved with the smell. :)

[Kramer]

I went with the vents a long time ago, pic is on gojeep's site ther ein the writeup. And the electric fan, see that writeup too. It's cheap and easy to do.

BTW how much is a water pump. might pay to have a spare for summer. Group buy??

[EwenM]

i spent the money on a fan hub and then removed it, the noise was extreme plus i could notice the power loss, so i fitted an electric fan and wired it with a relay to the A/C fan it works great whenever the ac is on and over 80kph its ok without a fan but get in heavy traffic on a warm day and it slowlly gets hotter and hotter ( as you would expect) i believe that raising the hood or vents is the answear as i dont think there is any air flow through the radiator at low speeds without some form of fan assist

Ewen

[jake]

I decided to lift the rear of the bonnet slightly just to see how much adding ventilation to the engine bay would help before cutting into the bonnet to add vents.

Drove to work today in 26 degree heat (peak hour traffic and a one hour trip)

temperature did not go beyond 95 unless idleing at lights waiting for thermo fans to cut in then it dropped straight back to 95.

Also noticed I had a cool (to touch) bonnet when I parked at work, normally you could fry an egg on it!

So yes it does work, I only put 5mm spacers in there so you hardly even see the gap unless you know it's there, so if there are no real negatives about raising the bonnet slightly I will probaly just leave it the way it is.

[EwenM]

great looks like that the project for this weekend

Ewen

[Steve F]

The only thing that bothers me about raising the rear edge of the bonnet is if a hose decided to let go. All that steam and water is going straight over the windscreen which in turn means you have little to no visibilty. I think you'll find that it is illegal to raise the rear edge because of this but I could be wrong. I still might do it though ;)

Cheers
Steve

[jake]

This is why a car has windscreen wipers :)

[jake]

Hey Ewen, it's not much of a project it only took me half an hour last night, I used approx 5 to 8mm nuts, didnt get exact measurents, as spacers (obviously larger than the thread on the bolts so they slide over easily) and used some longer bolts, the stock ones grabbed ok but I had some longer ones in the shed so my thoughts are the more thread in the hole stronger the grip.
The cooler under bonnet temps can only help in prolonging the life of hoses, batteries etc etc etc.

[EwenM]

i thought of getting a nylon bread board and cutting a couple of strips drilling them etc
i think that would give me about 8 to 10 mm

as for legallity, those 8 x 15 rims with 3.75 pack spacing and those longer shackles and 3.5 inch lift pretty much takes care of that

Ewen

[Steve F]

i thought of getting a nylon bread board and cutting a couple of strips drilling them etc
i think that would give me about 8 to 10 mm

as for legallity, those 8 x 15 rims with 3.75 pack spacing and those longer shackles and 3.5 inch lift pretty much takes care of that

Ewen

True, just thought I'd mention it as I've had a hose blow before and you'd have to be quick with the wipers to clear the windscreen ;)

Cheers
Steve

[EwenM]

yeah i'm not disagreeing with you on that score i would prefer not to raise the bonnet or cut vents in it ( but for me raising is preferable to cutting holes) i like gojeeps imported bonnet but i can not justify the cost, and i like the possibility that a cooler under bonnet area might extend the life of some of the hoses battery etc

i know some one who has raised his (Jon) and he seems to be happy with it, on a US sit it was discussed and some one raised the concern of rain runoff getting into electricals??? dunno maybe worth keeping in mind

at 340000 i have to again replace the oil filter adapter o rings, i guess because of the heat, and as said before on a hot day after a long drive you almost need gloves to open the bonnet so if raising it does the job and its virtually free its worth a go

Ewen

[jake]

There are no real electricals in that area, vents would have the same issue either way.
As you just pointed out it's a free mod and if it does the job, go for it.

The coolant etc blowing over the winscreen is a concern but if you look at the underside of the bonnet there is an area that drops down before coming back up to the lip at the rear where it touches the rubber seal. This lower area would have to stop some of the spray if the unexpected happened.

But then I have been known to be wrong :)

good luck

[Gildo]

If you take the hood off completely all the hot air goes away......