[-QIK-]

Ok, since leaving townsville it seems my Jimny now likes to run hot when sitting at 100k's with aircon on.

I have replaced:

Thermostat, clutch fan hub, water pump, flushed out the old shity green coolant and have priddy pink coolant now.

Any thoughts? I'm looking at taking it to get the radiator cleaned out in the morning.

The temp gets upto 3/4 when at 100k's, then it seems to cool down slowly if you pull over . The thermo fan also comes on once it hits 3/4 temps.There doesnt seem to be anything blocking the front of the radiator, I was thinking that it might be the cores are blocked on the inside?

Only started having the problems once I replaced the coolant and water pump. Got me buggered.

[Gwagensteve]

Is the thermo fan running when the A/C is switched on? I don't know what the conditions are that call the thermo on, but I would have thought it should have come on well before 3/4 on the gauge.

Steve

[31zook]

Air pocket? And did you replace the fan clutch with a new one or 2nd hand one?

[Trypt]

Park it facing uphill and run it with the cap off until the thermostat opens.
should get rid of any air locks

[-QIK-]

Thermo fan comes on when you turn the aircon on. But if the aircon is off it also comes on when the temp gauge hits 3/4. Kind of like a safety I guess.

The clutch fan is brand new from Repco.

Our drive way is like a hill climb. I'll park it and try the cap off.

I did notice the old thermostat had a small bleed valve on it were as the new on doesnt. Not that this is going to make a diffreance as it was over heating before it was replaced and is still over heating.

[atari4x4]

raditator, a/c condensers caked in mud?

try removing the rad remove the shit that falls between the rad & a/c + clean all the fins.

[Travis]

Why does your thermo come on at 3/4?

[-QIK-]

Im guessing the thermo fan comes on as a safety for the engine? Only noticed that it comes on at 3/4 since i have been having these problems.

Just parked the jimny on a hill. (driveway) and a few small bubbles came out.

Radiator and condenser are clean. I can look through most of it fine. (bullbar/winch gets in the way)

Between the radiator and condenser is clean.

Im kind of thinking it might have blocked cores. With the new clutch fan fitted it doesnt seem to pull as much air through as with the old one I had filled with oil.

The heater still works fine so its not blocked.

Only thing I can put it down to is either the radiator core is blocked, or for some reason my car doesnt like pink coolant?

[atari4x4]

did it previously have green coolant?

mix the red & green stuff & you can end up with a globulous mix of sludgy jelly.

[-QIK-]

Yes it used to be green. Well a shade of green. I dont think it had been changed in a long time.

I did make sure it was flushed out properly.

I changed the thermostat this morning after draining the coolant. I didnt see any signs of mixed coolant / sludgy jelly. Just all pink.

[royce]

yeah mixing coolant goes further than colours, the colours dont mean anything, even different models within the same brand cant be mixed

tell us how you flushed and changed the coolant when you did the waterpump and what else did you change at the time?

its possible its a cheap pump that isnt any good, or if you didnt use a good flush and then hose the cooling system out then mixed coolants could of blocked the radiator

[offroadjack]

radiator clean out is my suggestion. a fan clutch doesn't do much at 100 ks an hour, plenty of airflow at that speed. it is recommended to do a radiator clean out evry 5-6 years.. you be surprised how blocked the cores will get after a while.

[offroadjack]

and getting genuine coolant isn't much deerer then aftermarket stuff. if you do use aftermarket stuff i recommend tectaloy GOLD

[shakes]

-QIK- wrote:

I did notice the old thermostat had a small bleed valve on it were as the new on doesnt. Not that this is going to make a diffreance as it was over heating before it was replaced and is still over heating.

On top of royce's flush advice... Pull the thermostat and drill a 1/8th hole into it.

[offroadjack]

a thermostat is a vital part of the engine, can't believe people still get the cheapest nastiest crap they can get!. one of the things you should never go cheap on is cooling system items.. get a genuine one and it's never gonna fail on you. cheap insurance in my books! a failing thermos can stuff your engine real quick!

[offroadjack]

same goes for hoses..when i replace them i use genuine ones. they last 4-5 times longer then aftermarket rubber.

[-QIK-]

Clutch fan and thermostat are both Dayco items. I put them on the car this morning. The clutch fan has the same markings / print stamped on it as the old one that I removed (AISIN)

The thermostat I removed wouldn't open up after being placed in boiling water(89'), were as the new one did (88').

As I have done over the last 20 years of playing / working on cars, I turned the heater controls on, then I dump the water out of the radiator, either by the drain plug or removing the bottom hose with radiator cap off. While the hose is off I run fresh water through it to flush it out (put hose on, fill then pull hose off and repeat.)

Once I have done this I then put the bottom hose on again and disconnect the top hose from just the radiator. I then place my garden hose in the top where the cap is and set the hose to run slow (enough to keep the radiator full and water just flowing out the top hose outlet). After this is done I then start the car and let it run. Engine warms up, thermostat opens and lets out old water while sucking in clean water. I stop this once nothing but clean water comes out the top hose. Longest this has ever takin me is 20 mins.

While all that is going on I remove the overflow bottle and tip out any old water/ coolant. If the bottle is full of slimy shit I get a hose and flush it out. If lots of crap is stuck to the inside I get a handful of clean course sand and put it into the bottle. Place my hand over the top and start shaking. The sand acts like any good abrasive should and removes all the sticky sludge crap. Wash out and repeat if needed. <------- GOOD CLEANING TIP!

I then drop the bottom radiator hose and let all the water out. Put the bottom and top hoses back on and then add coolant/ water. Start engine again and let it run without the cap on topping up the water as needed.

Once I'm happy the engine has gone through a few thermostat open and close cycles I place on the radiator cap and take it for a good drive watching the temp. Normally my previous cars have run fine and never given me any problems, just this one.

Before I left Townsville I did an oil change on the engine and the coolant. Two hours after i did the coolant change I noticed it leaking on the ground. Thats when I changed the water pump.

Everything seemed to work fine until I was 2 1/2 hours out of town. Thats when it started running at 3/4 temp and I couldnt drive with the aircon on, had a mechanic fill the clutch fan with grease and that lasted another 2 hours. I drove the rest of the way with the heater and fan on high. Was a hot trip to Brissy. Since being here I have done the new clutch fan and thermostat.

[Trypt]

By the sounds of it the rad may be partially blocked.

either that or a defective temp sender

[suzkboy]

Silly question but u have the heater core open when u bled the system as well. A lot of people forget to do it and that can make cars run hot to due to there still being air in it.

[-QIK-]

Yep, it was open as well.

[drewhoo]

I had tonnes of problems with overheating at one stage. Ended up fixing with these (some/most of which it seems your have done). Not sure how many of these fixes are smart, but worked for me (and I was desperate). May as well put them in one spot anyway

- Replaced fan clutch Jelly (made massive improvement on fan pull)
- Flushed the radiator with high pressure (rust scales came out)
- Pressure washer externally to wash out fin mud etc, the fins on my rad were pretty straight)
- (note pulled the radiator completely out to do the above two, ive heard high pressure washers and radiators dont mix however I was running out of options)
- Replace thermostat with so-called "performance" once that turned on a few degrees less (found a fit with another model, cant remember which but was easy to figure out from repco catalogue)
- Drilled a single tiny (1/8") hole in the tstat just because, i think this was overkill, as the engine takes considerably longer to heat up to op temperature these days. Theres alot of arguing over the internet on this, both whether its a good idea, and whether to drill one or two holes.
- Also there was alot of rubber sh!t (i think used to pad under the bonnet) that had fallen down in front of the radiator, scraped it all out
- Did all the burping / air lock stuff written above

I was going to go down the honda civic radiator ($80) route but problems seem to be fixed (for now). The jimny radiator to buy new is ~350, bit much for me.

Mine primarily overheated in the sand, and when sitting idle in traffic. Sometimes after a day of thrashing it, the freeway would kill it too. Never goes above thermo opening temp now.

BTW the defective temp sensor idea may be a potential. When I was having trouble with overheating it never sat at 3/4 for very long, usually crept up to max temp less than ten minutes later, or back down to halfway if I stopped driving. Never saw it maintain 3/4 while driving with my issues

[droverdave]

Its quite possible, that all of the flushing and what not has dislogged a gunk from your engine, which is now clogging up your radiator.

The fact that it took ~2.5hrs for it to get hot sorta confirms this theory as it might have taken a bit of running time for the gunk to make its way to the radiator.

When flushing the cooling system, i always remove the radiator to flush it, that way you can turn it up side down and run water through it both ways. i tend to fill it up with water (cover hand on the lower rad pipe) then let all the water "gush" out, which tends to bring gunk with it. do this with the radiator up the right way, and upside down, more chance you will flush stuff out that way.

Clutching at straws a bit i know, but hey its just an idea.

[-QIK-]

Well i just dropped it off at the radiator joint. I'll see how it goes. They said it should be ready late this arvo. He told me the core is most likely the problem, as they have a tapered core (large at the top, smaller at the bottom) It slows the water flow to give it time to cool.

Fingers crossed.

[Samwich]

Same issue with mine atm...

Also happens when in Low range 4wd,

Temp just keeps going up, Replaced the same as you.
Made the thermo run all the time when the car is on, Same issue..
All i found to help was to leave the heater on full ball which cooled it down

Getting new radiator this week

[-QIK-]

Well i picked up the Jimny this morning.

All fixed!!

Works out the cores were 90% blocked. A combination of very old coolant, me flushing the system out and me having a slightly strong coolant mix.

Because it had old coolant, there was a sludge / crap buildup in the engine.

I flush it out, but by doing so also loosen the crap in the engine.

Add the new coolant, a little to much coolant.

The sludge comes loose and ends up blocking my cores.

Either way, everything I did was right in flushing the engine and radiator. It did need the cores roded to clean them properly.

Cost was $279 drive in drive out (new top tank fitted). Nearly the cost of a new radiator.

I know it works now, so its all good.

Thank you all for the replys and help.

[christover1]

I love a happy ending.

Wish I'd of changed my radiator before the rest of it