Overheating - Looking for troubleshooting steps

[surfkernow]

2.5 TD 4X4 - 1996

Symptoms

- Van over-heated to almost max on the temp gauge on a 9 minute journey
- Approx 1 litre of coolant was expelled from the expansion tanks over flow pipe (not enough to activate the coolant alarm)
- I was 2 minutes from home so let the engine cool and drove home, and added about a litre of water

I know I need to bleed and not drive the van but: I am looking at potential causes and areas to investigate.

I attempted to bleed it yesterday and got the upper and lower radiator hoses to get hot, but they did not feel like they had any water in them, they were very soft and i could squeeze them easily. Even after I had put the expansion cap on, it did not feel like the system was pressurised, there was not whoosh of air when i took the cap off

I am a little concerned the car overheated even though it was full of coolant, it only lost appox a litre and not enough to trigger my coolant alarm, which i found out did work when I was going through the bleed process yesterday. It still needs to be bled. Is 9 minutes even enough time for the thermostat to open? I have ordered some UV dye so I can add this to the coolant to see if I have a leak.

Has anyone got any pointers or troubleshooting advice? Thank you for your help

[Northern Bongolow]

Go on YouTube a look for 3 bids on how to bleed a bongo.
Have a good look round first as there may be evidence of a leak somewhere and fix this first.

[mikeonb4c]

2.5 TD 4X4 - 1996

Symptoms

- Van over-heated to almost max on the temp gauge on a 9 minute journey
- Approx 1 litre of coolant was expelled from the expansion tanks over flow pipe (not enough to activate the coolant alarm)
- I was 2 minutes from home so let the engine cool and drove home, and added about a litre of water

I know I need to bleed and not drive the van but: I am looking at potential causes and areas to investigate.

I attempted to bleed it yesterday and got the upper and lower radiator hoses to get hot, but they did not feel like they had any water in them, they were very soft and i could squeeze them easily. Even after I had put the expansion cap on, it did not feel like the system was pressurised, there was not whoosh of air when i took the cap off

I am a little concerned the car overheated even though it was full of coolant, it only lost appox a litre and not enough to trigger my coolant alarm, which i found out did work when I was going through the bleed process yesterday. It still needs to be bled. Is 9 minutes even enough time for the thermostat to open? I have ordered some UV dye so I can add this to the coolant to see if I have a leak.

Has anyone got any pointers or troubleshooting advice? Thank you for your help

I'm no techie, but I'm just wondering if the system pressurised rather than boiled over as such. The LCA wont generally go off in a bubbling header tank as it understandably doesnt get a dry detector. Its possible you may have a head/head gasket problem. You could try starting it from cold and see if the top hose very quickly goes firm, as this would suggest a head/gasket leak rather than normal heat/ pressure expansion. This should be done after having refilled and - ideally - bled (if it will let you of course - it may not if there's a head/gasket problem). Good luck & kerp us posred.

[teenmal]

It would be worthwhile having a look at the water pump assy.

[surfkernow]

Hello Northern Bongolow, mikeonb4c and teenmal, thank you for your replies. I am still waiting for my UV dye to arrive before I progress but I definitely have a leak as, I have filled the expansion tank to max at nigght and checked in the morning to find the expansion tank below low.

Teenmal, I think you're right about the water pump and it is my hunch, I can see it is wet below the pulleys when I shine my torch from above the engine, but I will wait for the UV dye to arrive to confirm this.

There is not point bleeding the system at the moment as there is clearly a leak so i will only end up drawing air in.

I will keep you guys updated and I do appreciate the help. Thank you

[mikeonb4c]

Hello Northern Bongolow, mikeonb4c and teenmal, thank you for your replies. I am still waiting for my UV dye to arrive before I progress but I definitely have a leak as, I have filled the expansion tank to max at nigght and checked in the morning to find the expansion tank below low.

Teenmal, I think you're right about the water pump and it is my hunch, I can see it is wet below the pulleys when I shine my torch from above the engine, but I will wait for the UV dye to arrive to confirm this.

There is not point bleeding the system at the moment as there is clearly a leak so i will only end up drawing air in.

I will keep you guys updated and I do appreciate the help. Thank you

Interesting. I'm trying to figure out what caused the header tank to overflow. I guess air pulled in through leak point as system cools and then forming a bubble somewhere in the system that causes rapid expansion when engine next warms might be the explanation?

[surfkernow]

Hi Mike, I am not sure as I not that experienced at fixing cars, but I hope to find out what caused the problem and will keep you updated. Hopefully mu UV dye will arrive soon

[haydn callow]

9 mins is not enough time for the stat to open from cold if all is well.
Normally takes 30 to 50 mins during a normal bleed cycle as per the YouTube videos
As said, water pump could be the cause and if the impeller has failed I suppose it could warm up very quickly and overheat.

[surfkernow]

Hello Haydn, thank you for your reply, you're right , it is a long process : bleeding the coolant system that is. I have been watching the 3 part bleeding videos a lot in the past week. Are you in the video? I recognise the name Haydn from something Bongo related.

I bled the system again today, i went for a short drive and the temperature started to increase and my coolant alarm activated. I put all the heaters on max and the temperature came down. Topped up the coolant and when for another drive and this time the temperature stayed stable.

I will bleed the system again tomorrow as there was a serious amount of air in the system. I have a clear tube attached to the funnel at one end and the bleed pipe on the other, so I can watch air bubbles climb up the pipe . The record was a 15 inch air bubble I watched progress up the pipe into the bubble.

Still awaiting my UV Dye. My Hermes updated to say they mistakenly sent it to Doncaster...I am in Cornwall !!

[haydn callow]

Yep, one of the video stars....

[surfkernow]

Hi Haydn, good video, thank you.

I chatted to a mechanic today who had a brief look and noticed that the top radiator pipe and the water pipe under the driver's seat were rock hard and that the pressure was too high. I found a few places where it looked like pipes were weeping or wet, the main one was one of the water pipes to the rear of the van on the driver's side - see photo

https://imgur.com/S3ic0P0

I clearly have to replace a few pipes by the look of it. They are not dripping coolant but they are wet.

I have booked the Van in for a pressure test next Thursday and a sniff test. I won't drive it in the mean time but so far, it has not overheated again

[surfkernow]

Okay, i made some progress today. I have ascertained that when the Bongo is taken for a short drive there is a big build up of pressure and the upper radiator pipe and the pipe going into the engine under the driver's seat is rock hard. This happens after a few minutes. I watched as coolant was forced out of the top of the radiator where there must be a crack. See photo



It appears that such is the pressure before the thermostat opens that the pressure has cracked the top of the radiator. When the thermostat opens the pipes are all fine and the pressure is released and the coolant is not forced out the top of the radiator.


The pressure would also have caused the overheating problem at the start of this thread where over a litre of coolant was forced out of the expansion tank. I had only been driving a few minutes so the thermostat would not have had a chance to open.

Again, once the thermostat opens the pressure drops and all is good. Any ideas?

[g8dhe]

The radiators have a metal to plastic seal at the top and the crimping of the metal to the plastic can fail or under excess pressure you might even suffer bending of the plastic top.
I'm afraid to say it all points to a crack in the head allowing excess pressure to get into the coolant system.

[mikeonb4c]

Okay, i made some progress today. I have ascertained that when the Bongo is taken for a short drive there is a big build up of pressure and the upper radiator pipe and the pipe going into the engine under the driver's seat is rock hard. This happens after a few minutes. I watched as coolant was forced out of the top of the radiator where there must be a crack. See photo



It appears that such is the pressure before the thermostat opens that the pressure has cracked the top of the radiator. When the thermostat opens the pipes are all fine and the pressure is released and the coolant is not forced out the top of the radiator.


The pressure would also have caused the overheating problem at the start of this thread where over a litre of coolant was forced out of the expansion tank. I had only been driving a few minutes so the thermostat would not have had a chance to open.

Again, once the thermostat opens the pressure drops and all is good. Any ideas?

Hmmm. Sounding a bit like head gasket / head

[surfkernow]

Yes, i am resigning myself to it being the Head Gasket, I am just exploring everything first. I posted on FB earlier with a photo of where coolant is leaking from, which makes little sense. See photo.



I had to wait for it to get dark to use my UV torch, but i saw what I thought was coolant dripping from this location, because it was glowing green so i knew it was the dye I put in the coolant system earlier today. Is it coolant or oil that has been mixed with the dye i put in the coolant because the cylinder head has cracked?

I am going to check at first light tomorrow and will update.

Thanks for all the contributions.