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Cooling system query

  • RiverRatJimny
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23 Feb 2020 12:28 #218936 by RiverRatJimny
Cooling system query was created by RiverRatJimny
Hi
So my Jimmy has had cooling system issues for the whole time I've had it (18 months). Any insights gratefully received.
It had a slow leak from one of the lower rubber pipes for ages, and has overheated probably 3/4 times (when I hadn't topped it up for a week or so). Guilty of neglect I know. It also had no heat in the cabin for driver. So feeling that it was time to help it out I replaced that leaking pipe at MOT time, and at the same time I flushed the heater matrix and then drove it as usual. So now there was some heat in the cabin (not crazy hot I'll add- more warm than hot) and it seemed to stop leaking. Next drama was the top hose to the rad split whilst the wife was on the school run, so I replaced that and the thermostat at the same time. The hose was literally paper thin where it bends - it's an old Jimny (98) so I put it down to just being old.
Anyway we started noticing that there were drips coming out of the exhaust, looked and felt like coolant, and the exhaust was quite smoky, there was also less heat in the cabin again. Uh-oh! Check oil- no problem, check coolant and rad cap- no residue or oily milk, no exhaust smells on the cap, nothing, but it did need topping up again.
So I decided to do a full rad flush, flush the block, and the heater matrix again (I didn't do the rad or block the first time I did the heater matrix) and see how it goes. I've done that last night and this morning - the rad is now clear, a lot of brown water has passed through and come out! Its taking 10/15 mins to heat up, theres no pressure in the rad whilst its running - just the expulsion of air bubbles periodically (e.g. when thermostat opens). I made a little header funnel and it stays perfectly level once it's full, no movement or boiling over. The exhaust is a bit smoky from cold- but it is clearing after a few minutes, there are a few drips of water coming out of the exhaust - we have had some seriously deep floods lately, and I'll confess that I've driven through them, I guess that could explain water in the back box? It's not running hot, and hasn't overheated since the top hose split (fortnight ago).
I'm planning to refill the system in a minute with new coolant and see how we go.
I am a bit concerned about the exhaust thing- how would coolant be getting pushed out of the exhaust? Wouldn't that surely give some other clear symptoms of engine trouble? Ps- its generally starting/running/idling seemingly fine, apart from our paranoia! Happy Sunday

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  • Lambert
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23 Feb 2020 16:21 #218948 by Lambert
Replied by Lambert on topic Cooling system query
Some water is inevitable in the exhaust as petrol burns wet unlike diesel and at this time of year it will have condensation in it too. I wouldn't be too paranoid about that. If however it's belching clouds of sweet smelling steam out of the exhaust that is a big issue. If with the rad cap off it produces the odd bubble and then settles down that is good, as opposed to a constant stream of bubbles when running which is bad. Did you use a chemical cleaning solution to flush it or just water? Liqui molly is good if you didn't use any and helped bring my heater back to life very well. At the moment I would suggest it is all about right and just needs observation.

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23 Feb 2020 22:06 - 23 Feb 2020 22:07 #218977 by Scimike
Replied by Scimike on topic Cooling system query
What Lambert said, time to keep an eye on it and relax.
If you are not loosing any coolant then I would not be concerned, the steam in the exhaust is condensation. If you are using coolant then it's time to keep looking. The radiator hoses would be the first thing to change, they fail with age and at 10 years old are noticeably weaker than a new hose (as you have found out). After that it gets a little harder to find the leak, but not impossible. Avoid the miracle in radiator sealants if you can, they will bung up a weak heater matrix as well as any minor leaks.
Mike

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Last edit: 23 Feb 2020 22:07 by Scimike.
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23 Feb 2020 22:26 #218978 by Max Headroom
Replied by Max Headroom on topic Cooling system query
I've recently cleaned my system out and would 100% agree with Lambert and Scimike on this. Just keep a good observation on the coolant level for now.

Like you, my heater isn't great which is why I did mine, flushing the matrix out in both directions, with fresh softened water. I have certainly imprioved the heating but I'm not out of the woods yet because my heater is definately not as good as my neighbour's Jimny which kicks heat out like a furnace.
I had a leak from the thermostat housing two years ago which was dealt with by the garage, but I'm beginning to wonder if they changed the thermostat in the housing when they had it aapart (its a pig of a job) and that it may be stuck open,


IF IT AINT BROKE, KEEP FIXING IT UNTIL IT IS
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24 Feb 2020 22:22 #219029 by RiverRatJimny
Replied by RiverRatJimny on topic Cooling system query
Thanks. I've driven it about 30 miles today- very mixed rural and main roads. Running generally as I would expect, heater working much better. Checked coolant earlier and it was a third of the way up between low and full on the expansion bottle, radiator full. I'll check it again in the morning.

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