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[snoopyjon]

Hi guys, yep, me again!!

Decided to pick the kids up from school today in the Jeep, all seemed to go well until I was nearly home when she really started smelling.  Looked at the temp guage and wasn't in the red, but wasn't far from it...  Leaked a little something when I stoppped which has now evaporated, so assuming it was water/coolant.

The hose from the top of the rad is red hot, and if I squeeze it with the overflow bottle open, nothing happens in there.  Bottom of the overflow feels cold too, so think I've got a blockage somewhere...

Is there an easy way to flush the cooling system, or to diagnose where a blockage is...?  With the overflow bottle, I can see where the small hose goes in the top, but can't see anything coming out the bottom... Does it go straight into the bay from the bottle?  What's the best way to drain the system?

Thanks everyone!

Jon.

[sprintagogo]

The overflow bottle doesn't form part of the active cooling system. It's purpose is as an overflow, so if the coolant temp and pressure rises enough to blow past the rad cap the excess is direscted to the overflow bottle. once the engine cools down again the coolant from the overflow can be sucked back into the engine. This means that the coolant in the overflow bottle won't get warmer than the ambient engine bay temp.

Your overheating problems could be 1 of 4 likely culprits

1, sticking thermostat

2, ageing, sludged up rad internally or mudded fins externally

3, failed viscous fan

4, failed elec auxiliary fan

Point 4 is probably the easiest to diagnose, does the elec fan kick in when the temp is high?
point 2, what is your coolant like? brown sludgey mush isn't good. also have you been off-roading lately because a rad full of mud will not allow for the airflow needed for proper heat dispersal, especially when in slow moving traffic.

[snoopyjon]

Thanks very much for the detailed response!

It's definitely not point 4 as the fan was spinning a good 'un trying to cool stuff down.

Coolant in the overflow bottle is brownish, but no oil in there, and definitely not like sludge.  Not sure where else to check for sludge, is it just a case of taking the rad cap off to look?  Does the overflow get sucked back in automatically?  If I put coolant in the overflow, will it reach the rad?

I'm hoping it's not a failed viscous fan, as I have no idea what that is, or where it is :-)  I hoping the most likely culprit will be a blockage in the rad itself.  I haven't been off-road since March, but did hose (not jetwash) the fins down so they're clear.  I do have a spare radiator, just don't have a lot of skin on my knuckles at the moment from the rear lift shackle replacement I did last weekend :-) 

If it is the rad that's blocked, is it possible to clear that out?  I'd rather try that before replacing it...

Thanks again,

Jon.

[Panic mechanic!]

the idea of the expansion bottle is to allow for coolant to expand into it  when the engine gets too hot then as it cools, the vacuum in it sucks it back in, thats the theory. There should be some fuid in there all the time , it should have marks on it to show you the levels.

[snoopyjon]

the idea of the expansion bottle is to allow for coolant to expand into it  when the engine gets too hot then as it cools, the vacuum in it sucks it back in, thats the theory. There should be some fuid in there all the time , it should have marks on it to show you the levels.

Ok cool.  Yep it's got marks on it, and is slightly below the Low mark.  So it's safe to top the coolant up in there or do you put it straight in the rad?

Sorry for the really stupid questions..!

Thanks,

Jon.

[Nosebolt]

when cold (that's quite an important) check the rad level is full then top up the expansion bottle to mid point between the high and low

[Dave69]

remove a coolant hose and dump the coolant use a hose to flush water through one way then the other until clear water can be seen. top back up with a 50/50 water anti freeze mix, then see what the temperature will do, you could fit a new thermostat at the same time

[daggie]

sound like the t/stat

[snoopyjon]

Ok... Stupid question of the day - where is the thermostat on one of these...?

Cheers,

Jon.

[Mike Pavelin]

Ok... Stupid question of the day - where is the thermostat on one of these...?

Cheers,

Jon.

In the thermostat housing

[Dave69]

front of the engine just near the top.

something like this

[snoopyjon]

Thanks for all the responses folks, dumped the water from the rad, I say water, as it was just that.  There was no coolant in there at all!  Flushed it all out with clean water from the hose, had water running nice and clear, then filled back up with 50/50 coolant.  Had a bitch to start it afterwards though, starter was turning like a good 'un, but just wouldn't fire.  I did forget to put the pipe from the top of the engine block to the air box back on, and there was a nice smell of petrol... Left it ten minutes after connecting the pipe, then tried again.  With foot on the throttle she then fired up, but I had to keep my foot on the gas for about 5 minutes as it wouldn't idle.  Not sure if I got something I shouldn't have wet with the hose, but once some temperature started to build I was able to take my foot off and then all seemed ok.   I let it get nice and warm, then switched off and let it cool down again to check the levels.  Had to top up a bit again, then fired her up and let her get really hot.  Got to just over 100 degrees according to the temp guage, then the fan cut in and pulled it down to just under 100.  I let it do this three or four times to check it wasn't going to get too hot again, and thankfully it didn't. 

I was going to attempt to change the thermostat as well, but couldn't get to the lower bolt because of the belt, and didn't want to start taking that off just yet. 

Thanks again for all the responses, I appreciate it's a bit of a one way street with me at the moment, as I seem to be asking lots, but not giving much back...!  I'm sure as time goes by and others have the same issues as me, I can start to help out others as I've been helped.

Cheers,

Jon.

[Bulldog67]

Result hopefully then Jon