How hot does diesel engine need to be before fans cut in?

[langtoftnick]

Having more problems with cooling system.

Had a leak, so fixed that, refilled and bled system. All ok, but yesterday (a week after) engine went to 95 and the temp alarm went off. Plenty of water in system, but bottom rad hose was cold. It has a new thermostat.

Today, drained, removed thermostat, put it in pan of water and heated it. It opened ok so replaced it, refilled and bled (according to approved method in the video) Bottom hose got hot, then thermostat opened, got a burp, bottom hose went cold again and stayed cold. Engine got hotter and hotter. Laser gauge shows top of thermostat housing at 95 and bottom at 58 why the hell hasn't the stat opened?

In desperation remove stat and cut out the valve so permanently open. Now hoses both get hot and engine ok at about 70 while moving but idling got to 87 without the fans cutting in before I chickened out and gave up after 7 hours covered in antifreeze.

What temp should fans cut in? Where is the sensor for it? I have a low coolant alarm and a a Haydn temp watchdog thank god, saved my engine last night. I love our bongo but hate the bongo "cooling" system!

[Northern Bongolow]

have a read of this, it may help.

http://www.igmaynard.co.uk/bongo/forum/ ... re#p634328

the sensor is mounted on the drivers side of the cylinder head, just up above the starter motor. 18-840c on here.

http://lushprojects.com/bongopartsmk2/c ... mgno=.html

[rita]

Having more problems with cooling system.

Had a leak, so fixed that, refilled and bled system. All ok, but yesterday (a week after) engine went to 95 and the temp alarm went off. Plenty of water in system, but bottom rad hose was cold. It has a new thermostat.

Today, drained, removed thermostat, put it in pan of water and heated it. It opened ok so replaced it, refilled and bled (according to approved method in the video) Bottom hose got hot, then thermostat opened, got a burp, bottom hose went cold again and stayed cold. Engine got hotter and hotter. Laser gauge shows top of thermostat housing at 95 and bottom at 58 why the hell hasn't the stat opened?

In desperation remove stat and cut out the valve so permanently open. Now hoses both get hot and engine ok at about 70 while moving but idling got to 87 without the fans cutting in before I chickened out and gave up after 7 hours covered in antifreeze.

What temp should fans cut in? Where is the sensor for it? I have a low coolant alarm and a a Haydn temp watchdog thank god, saved my engine last night. I love our bongo but hate the bongo "cooling" system!

I think you are needing to raise the bar on the temp gauge trigger, the thermostat on these old oil burners does not (usually)Fully Open until the temperature reaches 95c.

Good Luck.

[haydn callow]

Suggest you set the temp alarm to 100C, and put a new stat in.

[langtoftnick]

Thanks for everything, again!

Going to try a new stat, i suppose they have to go wrong at some point but this one was only a year old. When I bought the bongo the previous owner had also removed the valve so I wonder.....

Up til this event it had never got hotter than 84 when idling, only creeping up to 90 when restarted after a brief stop.

Useful to know the fan comes on when a/c on, had assumed the noise was the blower. Does anyone know what temp should trigger the rad fan? I'd like to know that the sensor/relay is working as it should before the summer.

[g8dhe]

Good thread here http://www.igmaynard.co.uk/bongo/forum/ ... =3&t=48872 on the fans and operation.

[langtoftnick]

Replaced the stat and refilled and re burped it and everything calmed down. CApped off the header tank to force any gas up the bleed pipe, and was a bit worried that seemed like a continuous flow of occasional bubbles for about 20 minutes after the engine got up to 85 degrees or so... thought that I had a blown gasket which was throwing exhaust into the cooling system (even though a dye test had previously shown there was no problem there)... then there was an enormous explosion of bubble, topped up the header tank and it all went clear with no more.

Must have been a recalcitrant airlock in there somewhere that took about 30 minutes at 2500 revs to shift.

Since then been to birmingham and back and never missed a beat... famous last words.

Anyone ever tried a closed loop system? After the intial see-sawing I thought about getting a header filler cap and fitting a hose connector to it, running that to a separate (temporary) header tank, with a second connection to the bleed pipe, Then just fill it up and let the engine run. Saves standing there for an hour with a scalding funnel of water in your hand.

Think it would work?

[helen&tony]

Hi
That's a yes and no!
The problem is that you are putting aerated coolant back into the system if you get a very "bubbly" bleed...I've had some bleeding sessions with a few good bubbles, and another with myriads of little bubbles, more like froth, and you wouldn't want that lot in the system!
Cheers
Helen

[Northern Bongolow]

Replaced the stat and refilled and re burped it and everything calmed down. CApped off the header tank to force any gas up the bleed pipe, and was a bit worried that seemed like a continuous flow of occasional bubbles for about 20 minutes after the engine got up to 85 degrees or so... thought that I had a blown gasket which was throwing exhaust into the cooling system (even though a dye test had previously shown there was no problem there)... then there was an enormous explosion of bubble, topped up the header tank and it all went clear with no more.

Must have been a recalcitrant airlock in there somewhere that took about 30 minutes at 2500 revs to shift.

Since then been to birmingham and back and never missed a beat... famous last words.

Anyone ever tried a closed loop system? After the intial see-sawing I thought about getting a header filler cap and fitting a hose connector to it, running that to a separate (temporary) header tank, with a second connection to the bleed pipe, Then just fill it up and let the engine run. Saves standing there for an hour with a scalding funnel of water in your hand.

Think it would work?

as you got it up to 85 deg or so (where was that measured) you may have or may not have got the stat opened, this opens at 83 (first stage) then as it gets hotter the second stage of the stat opens and closes the bypass hose link off, this floods the head with the coolest water available, from the rad. this pushes the last remaining air that is trapped out of the bleed pipe. this can happen in one large burp or slower little burps.
it sounds like you may have been lucky, 30 mins at 2500 revs with no or very little water in the head usually is more than enough to cook the head.

have a read of this link, its very good, page 6 is about the stat, but its all good.

http://www.igmaynard.co.uk/bongo/forum/ ... ng#p360049

[Simon Jones]

Anyone ever tried a closed loop system? After the intial see-sawing I thought about getting a header filler cap and fitting a hose connector to it, running that to a separate (temporary) header tank, with a second connection to the bleed pipe, Then just fill it up and let the engine run. Saves standing there for an hour with a scalding funnel of water in your hand.

Think it would work?

Also yes and no, but for a different reason . With the expansion cap off there is no pressure to push the water uphill from the bleed pipe to the header tank. However, I knocked up a pumped bleeding system many years ago which does the job nicely. It's very Heath Robinson: on/off valve in the end of bleed pipe which feeds a windscreen washer reservoir which pumps coolant back to the header tank. By adjusting the flow rate via the valve, it can be set such that it flows nicely around without all the fannying around with funnels and buckets.







A couple of points. The washer reservoir I used had twin pumps and after about 6 years of occasional use one packed up either due to heat or general old age. Yes, if you are not careful with the flow you can end up pumping aerated coolant back into the system, but the header tank will allow the bubbles to disappear so it's not really a problem. This was mk1 version and I now have a remote switch on the pump so I can stand back with cup of tea in hand and watch the level in the header tank. I have plans to refine it further but I'm now running on long life coolant so I'm not planning on needing to bleed it for another 3 years

[helen&tony]

Hi Simon
I must admit to having had plans for something along the same lines, but we have it down to a fine art now, and the only thing "Him Indoors" gripes about is putting the bung back in and scalding his hands. Where did you get your plastic tap for the bleed hose?....that's been promised to "Him Indoors" so he can just turn off when finished, and I'll replace the bung!
Cheers
Helen

[Simon Jones]

Hi Helen, the tap came from a box of John Guest pipe fittings I bought at a car boot sale from a chap who used to fit beer lines in pubs. The valve is like one of these: http://www.johnguest.com/products/drink ... er/valves/

While I know the valve is up to withstanding the pressure (10 bar @ 65C) but I'm not so confident on the long term use at high temperatures so when I've finished bleeding I clamp the pipe and then refit the bung so there is no risk of it anything coming out.

[wonkanoby]

http://www.ebay.co.uk/itm/New-in-stock- ... 389wt_1190


ive often wondered if some thing like this in the bleed hose would not help

[haydn callow]

Just something else to fail and leak??

[helen&tony]

Hi
Thanks, Simon...I only want it to turn off when finished bleeding, then I'll pop the bung back myself...."Him Indoors" always burns his hands at that stage
Cheers
Helen