Page 2 of 2
Re: Overheat again
Posted: Fri Jan 08, 2010 5:43 pm
by nigelginny
When i rev the coolant does come out of the filler cap (when its warmed up) but i cant see any movement in the header tank, i think tomorrow i will check it at the radiator, i had a look at the rad earlier and was a bit concerned as the coolant looks very rusty brown but when i bled it the coolant showed no signs of this, ive decided to wait until the snow clears a bit then take the rad off and back flush it as best as i can. i may even consider taking the thermostat out and check that, if the thermostat stuck closed would this effect the heaters? any help appreciated
Re: Overheat again
Posted: Fri Jan 08, 2010 6:02 pm
by mikeonb4c
nigelginny wrote:When i rev the coolant does come out of the filler cap (when its warmed up) but i cant see any movement in the header tank, i think tomorrow i will check it at the radiator, i had a look at the rad earlier and was a bit concerned as the coolant looks very rusty brown but when i bled it the coolant showed no signs of this, ive decided to wait until the snow clears a bit then take the rad off and back flush it as best as i can. i may even consider taking the thermostat out and check that, if the thermostat stuck closed would this effect the heaters? any help appreciated
I'm trying to think if this would happen if a healthy pump was working against a closed thermostat. I reckon it suggests the the pump is working though (unless gas from a gasket leak is causing it). I don't like the sound of rusty brown coolant. If the stat is not known to be new and working then defo. fit a new one and see what happens. You should get an idea how well the pump is working by how well coolant pumps out the bleed hose when you bleed the system. The radiator has to be suspect for blockage/inefficiency too so may need to consider a new one. There's still enough to remain hopeful the head has gone again though (you need to get coolant tested for traces gases before you can know - since there is no steam/white smoke coming out of exhaust on start up and start up is good, it sounds like any head gasket problem will be chambers leaking combustion gas into coolant system (or oil system? does dipstick show good clean or black oil like it should) ).
I have a growing conviction that when head problems get mended, the underlying cuases may not get mended, which only invites the original problem to reoccur.
But with luck we may just get you out of this one without disastrous cost
Re: Overheat again
Posted: Fri Jan 08, 2010 6:13 pm
by nigelginny
I cant say that the pressure of the coolant when i bled the system looked slow, i havent checked the oil for traces of coolant yet, thanks for reminding me, i will check this tomorrow, i may try to get the rad off as well.
Re: Overheat again
Posted: Fri Jan 08, 2010 6:30 pm
by mikeonb4c
nigelginny wrote:I cant say that the pressure of the coolant when i bled the system looked slow, i havent checked the oil for traces of coolant yet, thanks for reminding me, i will check this tomorrow, i may try to get the rad off as well.
Before you drop the old coolant it would be good to test it for exhaust gas traces.
Next, whereas I might normally say just refill with pure water for testing purposes, you've got to be careful in these freezing temps. Nevertheless, I wonder if the thermostat could be changed, then a fill with water (maybe hot water from the house, maybe with Radflush in it), a bleed done (which should reveal in passing the health of the pump and the fact the stat is opening OK - bottom hose gets warm/hot), and then a quick test to see if the temp gauge stays at 11.00 o'clock (shut down if it doesn't stay at 11:00 - this is workshop manual advise for bleeding a normal system anyway). Next, drain the system, and try and notice (or even measure) the rate at which water exits the rad to gauge how free flowing the rad might be. Drain it as soon as engine stopped so max amount of rust etc. is in suspension and comes out (Radflush in the coolant water should help encourage a purge). You then have choices. You could fit a new radiator (which ought to do nothing but good), or else get a Mason alarm (or TM2) and fit that so you can keep a close eye on exactly what the variations in engine temp are and whether cooling system efficiency appears to be marginal (if it is you'll want to fit a new rad.).
Hope these thoughts help. It would be good to get views of a cooling system expert on the above in case my advice is unsound.
Keep us posted.
Re: Overheat again
Posted: Mon Jan 11, 2010 12:22 pm
by nigelginny
I thought id have one last try at bleeding the system again this morning so i downloaded the instructions from bf, different from the one i searched the forum for before??? anyway took the bung out of the bleed hose, set it higher than the expansion tank, took the ex-tank cap off and filled the tank to the high level, i then idled the van for about ten mins, this got the temp up to about 11 oclock, then as per instructions i reved the engine for 6 mins at 2500 revs, this got the bottom hose warm, i wanted to get the hose hot so i revved it at 2500 rpm for 3 mins, this got the bottom hose hot eliminating the thermostat being at fault, the heaters warmed up nicely had them on hot whilst bleeding, well this seems to have worked (i hope, havent tried a very long journey yet snowed in, ran around our estate for about a mile steep hills)it seems the fault was ME not bleeding the system correctly, i remember topping up with abot half a litre of coolant about a month ago as the low level alarm sounded, it must have had air enter it then, we only use the van at w/ends so its taken this long for the air to get to the head and cause the overheating, i spose the snow /ice could have caused the l/l alarm to fail anyway i'll keep an eye on the coolant level more often rather than totally rely on the ll alarm, i must have a leak some where but i cant see anything yet, thanks to all who gave advice fingers crossed that shes ok now , and i think ive managed to talk the wife out of selling the beast (if everthing turns out ok).
Re: Overheat again
Posted: Mon Jan 11, 2010 12:28 pm
by mikexgough
Don't forget.............. Check your coolant when cold in the morning.... £ to a penny it will have dropped - then after that all should be okay......
Ask any of the specialists..... Wheelquick, Bell Hiil etc.- they will tell you that the coolant will have dropped overnight after a full coolant change.........also see the Jap sites like Masabee......same result, new coolant drops overnight/top up then your sorted......
Re: Overheat again
Posted: Mon Jan 11, 2010 2:50 pm
by mikeonb4c
nigelginny wrote:I thought id have one last try at bleeding the system again this morning so i downloaded the instructions from bf, different from the one i searched the forum for before??? anyway took the bung out of the bleed hose, set it higher than the expansion tank, took the ex-tank cap off and filled the tank to the high level, i then idled the van for about ten mins, this got the temp up to about 11 oclock, then as per instructions i reved the engine for 6 mins at 2500 revs, this got the bottom hose warm, i wanted to get the hose hot so i revved it at 2500 rpm for 3 mins, this got the bottom hose hot eliminating the thermostat being at fault, the heaters warmed up nicely had them on hot whilst bleeding, well this seems to have worked (i hope, havent tried a very long journey yet snowed in, ran around our estate for about a mile steep hills)it seems the fault was ME not bleeding the system correctly, i remember topping up with abot half a litre of coolant about a month ago as the low level alarm sounded, it must have had air enter it then, we only use the van at w/ends so its taken this long for the air to get to the head and cause the overheating, i spose the snow /ice could have caused the l/l alarm to fail anyway i'll keep an eye on the coolant level more often rather than totally rely on the ll alarm, i must havee a leak some where but i cant see anything yet, thanks to all who gave advice fingers crossed that shes ok now , and i think ive managed to talk the wife out of selling the beast (if everthing turns out ok).
Sounds encouraging. Did water gush healthily out of the bleed hose (a rough and ready indicator I'd have thought on how well the water pump is working)?
There is a theory on here that a pinhole leak can push coolant out during heating / expansion (but in quantities hard to spot) and then - as system cools, draw air in through the pinhole. this air gravitates to a suitable pocket point. When the system next heats and circulates, the air may get burped out of the system resulting in a the coolant loss showing in header tank level drop. Or it may get stuck in a pocket, and because air expands much more with heat than coolant, it may create excess pressure and cause the expansion tank cap to vent so that a brew up takes place. Its only a theory, as far as I am aware, but it seems plausible. If you could get some u/v dye to put in the coolant (and a u/v torch) that would help pinpoint any leak.
Re: Overheat again
Posted: Mon Jan 11, 2010 3:02 pm
by miker
Put a new thermostat in just to be sure, they only cost around 12 pounds and best to start off with it known to be working properly....
Re: Overheat again
Posted: Mon Jan 11, 2010 3:08 pm
by nigelginny
That does sound plausable, good news though, ive just come back from a ten mile drive and no overheat, i wonder how many other owners have not correctly bled the system and caused serious damage? i know for a fact that last year when i had the same problem if i had followed the instructions to the letter then i would not have had to pay out for a new head, is there a diagram on here that not only explains the reason for bleeding and the importance of getting it done properly. ive got a service booked soon so i'll get thethermostat changed then maybe get the top and bottom hoses changed to the ones flippa sells, just to eliminate them.
Re: Overheat again
Posted: Mon Jan 11, 2010 3:39 pm
by mikeonb4c
nigelginny wrote:That does sound plausable, good news though, ive just come back from a ten mile drive and no overheat, i wonder how many other owners have not correctly bled the system and caused serious damage? i know for a fact that last year when i had the same problem if i had followed the instructions to the letter then i would not have had to pay out for a new head, is there a diagram on here that not only explains the reason for bleeding and the importance of getting it done properly. ive got a service booked soon so i'll get thethermostat changed then maybe get the top and bottom hoses changed to the ones flippa sells, just to eliminate them.
Yup, and remember that if the above theory is correct that air may slowly get pumped back into the system, so you need to track down that leak.
Re: Overheat again
Posted: Mon Jan 11, 2010 4:21 pm
by handyman
Good job you didn't go to get the thermostat out, co's it's a f**k*n bitch to get at
Whoever designed the bongo cooling system must have been on somethin at the time.
Must have been bad sushi
Re: Overheat again
Posted: Mon Jan 11, 2010 6:06 pm
by nigelginny
I looked at it and thought hmmmm, pay someone
Re: Overheat again
Posted: Mon Jan 11, 2010 7:41 pm
by Aunt Trumpet
handyman wrote:Good job you didn't go to get the thermostat out, co's it's a f**k*n bitch to get at
Whoever designed the bongo cooling system must have been on somethin at the time.
Must have been bad sushi
nigelginny wrote:I looked at it and thought hmmmm, pay someone
To be honest guys, I've had mine out twice, once to test it and once to change it just to be sure and its not too bad. Out.....tested.....In....all within about 30 to 40 mins.