Cooling problerm - I'm competely foxed....
Discussion
My 4.0L Chim is running hot, around the 90 degree mark whilst cruising, should be nearer 80 degrees. In traffic it creeps over and is in danger of overheating. It all started when it nearly overheated due to fans fuse blowing. This problem solved and fans are working. Coolant bled and topped up. System is pressurising. Have exhausted my limited knowledge and experience. Any help / clues / advice gratefully received.
tvrbob said:
You say you've bled the system. Did you do this by priming the swirl pot and top hose directly? If you primed via the expansion pot there is every likelihood that you could still have an airlock
Could you expand on this please? (My knowledge v. limited). I bled as per the description in the SH bible for serpentine engine - that is, I had the top cap off the swirl pot as well. Just thinking now that perhaps I didn't bleed it for long enough, as coolant was pushed out of the bleed screw on the rad as soon as I removed it. Would air come out straight away if there was an airlock? Cheers.
Don't think otter etc knackered as fans coming on exactly at specified temperature and staying on as guage continues to creep upwards.
>> Edited by andy400 on Friday 18th March 12:40
Last year I had a dodgy otter that came on at the right temperature but didn't stay on for long (initially I thought it was ok as the fans were cutting in and out). Mine had the same symptoms as yours. Replaced with standard otter and everything ok again (touch wood...).
In terms of bleeding I think you need to follow the advice in the handbook or Steve H manual to the letter and not stop part way through the process.
In terms of bleeding I think you need to follow the advice in the handbook or Steve H manual to the letter and not stop part way through the process.
andy400 said:I'd start by saying your symptoms would not lead me to think of an airlock. I comment simply because you mentioned bleeding the system in your original post. Airlocks give symptoms of erratic temperature swings and cooling fans failing to come on even though the temp gauge reads high. The reason is that a slug of relatively cool air is moving around the system. When it's at the fan switch the fans will fail to operate. When it's at the pump circulation will stop and water in contact with the block will boil, this usually jogs the water and circulation resumes.
Could you expand on this please?
In my experience the only way to remove air from the top hose is, with the engine off and cold, remove the brass screw from the swirl pot and top up to overflowing. Replace the cap and repeatedly squeeze the top hose listening for the sound of water. As you squeeze the hose any air will be agitated into the small headspace in the swirl pot. Take the swirl cap off again and refill, recap then squeeze the top hose again. Keep doing this until there is no air to be found in the swirl pot headspace. Be aware the swirl pot cap is difficult to open. The pot is soft aluminium and will not survive a bashing. Better to use gentle leverage rather than a hammer.
andy400 said:
My 4.0L Chim is running hot, around the 90 degree mark whilst cruising, should be nearer 80 degrees.
Why do you say that about 91 deg is considered to be the ideal for the RV8.
timewind said:
I think a stable 90 degrees is normal. At least at my 500 it´s always around there. Also the gauges are less then accurate. As long as temp don´t pass 100 I am not freightened.
Good summary IMHO.
Overheating with the fans on suggests to me that either the fans aren't moving cool air through the radiator, or the water pump isn't moving hot water through the radiator, or the radiator has air in it, or the radiator is silted up. In your case an air lock in the radiator is the most likely explanation given that it was working previously. The radiator will tend to collect any air bubbles that reach it, and it's quite likely that bubbles will have reached it while you were filling the rest of the system especially if you didn't bleed the rest of the system thoroughly. You should bleed the radiator separately after you've bled the rest of the system, and bleed it again every six months or so.
19560 said:
My 4.0L Chim is running hot, around the 90 degree mark whilst cruising, should be nearer 80 degrees.
Why do you say that about 91 deg is considered to be the ideal for the RV8.
timewind said:
I think a stable 90 degrees is normal. At least at my 500 it´s always around there. Also the gauges are less then accurate. As long as temp don´t pass 100 I am not freightened.
Good summary IMHO.
The bible has the cruising temp stable at about 80 degrees and that's what mine was doing until this all started. Plus it gets significantly higher when stationary and has to be switched off, so something ain't right.
tvrbob: I have squeezed my top hose somewhat - had to it several times before the level in the swirl pot would stay at the top - does this mean there was air there that shouldn't have been. Also, whilst squeezing my hose (ooer) I noticed a sound of movement from what I think was the thermostat - I've presumed that this means that bit of kit isn't jammed?
I had a thread about a week ago as my cooling was poor. Went to Levens today and got a new stat and otter. Just taken out my stat from the car and it was an 88C(!!!) with allot smaller appature than the Leven 74C, so fingers crossed she may be better now. I will let you know how she is after the weekend.
>> Edited by anonymous-user on Friday 18th March 21:50
>> Edited by anonymous-user on Friday 18th March 21:50
>> Edited by anonymous-user on Friday 18th March 21:50
>> Edited by anonymous-user on Friday 18th March 21:50
Not saying this is your problem but I just changed my rad, no leaks but simply no longer cooling properly anymore. When I took it off and looked at the core I could see why, it was knackered.
Once you have covered the fan/otter/thermostat/bleeding side of things the rad may well be the way to go. I also fitted a slightly "earlier" otter switch, the cooling system has never worked better and now ready for summer.
Once you have covered the fan/otter/thermostat/bleeding side of things the rad may well be the way to go. I also fitted a slightly "earlier" otter switch, the cooling system has never worked better and now ready for summer.
Ribol said:
Not saying this is your problem but I just changed my rad, no leaks but simply no longer cooling properly anymore. When I took it off and looked at the core I could see why, it was knackered.
Once you have covered the fan/otter/thermostat/bleeding side of things the rad may well be the way to go. I also fitted a slightly "earlier" otter switch, the cooling system has never worked better and now ready for summer.
Agreed, If rad is not in tip top shape and even slightly below design efficiency then it needs changing. Did mine cos it was doing the same as u describe and now it never moves off 75-80ish. Fans come in and drop the temp in a matter of around 30 seconds in traffic. Hope that helps...
I would check that the temps on the guage are the same as on the engine with a IR thermometer or something similar. If that pans out then it might be worth flushing the system to make sure there are no blockages that are limiting flow.
After that I would look at the stat. They do fail and it is possible that the stress from the fans fuse dying has tipped the balance.
Is the rad leaking or weeping as low levels will cause the systems you are seeing.
After that I would look at the stat. They do fail and it is possible that the stress from the fans fuse dying has tipped the balance.
Is the rad leaking or weeping as low levels will cause the systems you are seeing.
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