Air Lock? considering removing the stat....

[Aunt Trumpet]

After overhaeting back in July I discovered a slight leak from the coolant rail that runs to the rear heater. I replaced the rail and bled the system, I also replaced the stat with a new one because the bottom hose seemed to take a while to get hot and I thought it might be sticky.

Anyway, after 2 months of faultless motoring its happened again!....overheated. Luckily it wasn't far from home so after a cool down I nursed it back with no problems. I've had a good look around and noticed a very slight weeping beneath the rear heater but this time from one of the pipes that comes out of the bottom of the heater itself. Also it will idle all day long on the drive with no overheating but a short drive down the road sees it creep up above normal and the bottom hose is not getting hot warm again!! Surely not the stat again?...so my questions are:

Can I remove the stat completely or do I need to remove the innards leaving the rubber seal so I dont get a leak from the housing?

And, how easy is it to bypass the rear heater altogether? Is it just a case of disconnecting the flow and return from the heater and joining them up?

Thanks for any help...

[dandywarhol]

Removing the stat is only disguising a problem which will only come back to haunt you IMO

Bypassing the rear heater seems a better idea - a piece of rubber pipe should be all thats required to link the feed and return to the matrix

[missfixit70]

From my investigations on removing rear heater, you don't need to provide a bypass circuit, just block off the flow & return to the rear heater. Here's the original thread - http://www.igmaynard.co.uk/bongo/forum/ ... =3&t=29530 .

[Aunt Trumpet]

Perhaps removing or modifying the stat isn''t the long term answer but I need to get it back on the road sharpish as it's my wifes main transport, I still can't understand why the bottom hose is still cool though. Could the air lock be where the stat is causing it not to open?

I am going to check out the rear heater leak tomorrow, hopefully this will be a quick temporary fix.
also, where can i get some UV dye from to check out any potential problems?

[missfixit70]

Haydn Callow should be able to sort you with some uv dye.

[bigdaddycain]

Perhaps removing or modifying the stat isn''t the long term answer but I need to get it back on the road sharpish as it's my wifes main transport, I still can't understand why the bottom hose is still cool though. Could the air lock be where the stat is causing it not to open?

I am going to check out the rear heater leak tomorrow, hopefully this will be a quick temporary fix.
also, where can i get some UV dye from to check out any potential problems?

Just in case Haydn doesn't have any at the moment, red coolant shows up a bright pink when a UV light is passed over it... I know that's not much use to you if you use blue/green coolant though!

[haydn callow]

got plenty of dye at the moment.....when it's gone it's gone...I will not be restocking.

[Aunt Trumpet]

Thanks, I'm going to have a go at isolating the rear matrix tommorrow. Looking from underneath it doesn't seem too difficult (fingers crossed). I'm going to go right back to the 3 way T-piece on the rail that runs from the front of rhe car and then join it up with the rail that runs accross the car to the nearside.

I'm also going to take the thermo out and put it back in again. I was wondering if the reason that I couldn't get the bottom hose hot/warm was because there was an air lock immediately above the thermo thus keeping it shut and not opening. So, removing the thermo and releasing it should clear it.

Does this sound feasable or a load of twaddle?

[missfixit70]

You don't need to join the pipes IMO, just block the feed & return to the heater matrix as discussed on the thread I linked to, I'm thinking of going back to this idea

Right, having had a poke about underneath & looking at lushprojects - http://www.lushprojects.com/bongopartsm ... mgno=.html



I'm thinking of removing the pipework rear of the two drawn on arrows at Z & Y, effectively replacing the t pieces with elbows, thus eliminating the rear heater from the circuit, as I'd imagine it to be with the non rear heater factory set up.
Any thoughts?

to gain some extra storage space possibly for a water tank as per Wellhouse conversions, or for a fridge compressor

[haydn callow]

I'm also going to take the thermo out and put it back in again. I was wondering if the reason that I couldn't get the bottom hose hot/warm was because there was an air lock immediately above the thermo thus keeping it shut and not opening. So, removing the thermo and releasing it should clear it.

Does this sound feasable or a load of twaddle?

That doesn't make any sense to me....I doubt the stat is anything to do with any problem.
How have you been trying to get the Bottom Hose Hot ??

[Aethelric]

Perhaps removing or modifying the stat isn''t the long term answer but I need to get it back on the road sharpish as it's my wifes main transport, I still can't understand why the bottom hose is still cool though. Could the air lock be where the stat is causing it not to open?

I am going to check out the rear heater leak tomorrow, hopefully this will be a quick temporary fix.
also, where can i get some UV dye from to check out any potential problems?

My bongo has been running without a stat fro a few thousand miles. The body of the stat is still there so it is sealed.


With mine, air gets into the system if the temperature goes up, so keeping the stat out keeps the temperature down. Not adviseable long term, but like your wife, I need it on the road fro another couple of months.

Of course you may have a different problem, so it may not work for you. But if you go down this route, then switch on the air conditioning when moving slowly. It switches on the radiator fans.

The stat is heated by coolant circulating in the bypass circuit so an airlock would not stop it opening. It is possible that you have air trapped in the head, maybe it entered by the leak in your heater system. If there is only a little, then there may be enough coolant circulating at a tickover to keep it cool, but not when pulling. Have you bled the system?

Dave

[Aunt Trumpet]

That doesn't make any sense to me....I doubt the stat is anything to do with any problem.
How have you been trying to get the Bottom Hose Hot ??

The stat is only a couple of months old so I'm not sure about it either, however I took it out and tested it in a pan of boling water and it stayed shut! I took it out, let it cool and re-tested several times and it worked ok. I tried to get the bottom hose warm last week before bleeding but it wouldn't happen. I revved and idled it on the drive for ages but nothing happened, when i took it on a short run it started to overheat (with all fans on etc) but the bottom hose stayed cool. Hence my quiery about the stat and air lock. Any other ideas why this may happen?

You don't need to join the pipes IMO, just block the feed & return to the heater matrix as discussed on the thread I linked to, I'm thinking of going back to this idea

I must admit I don't understand why you don't need to join the pipes? I by-passed mine this morning and it was quite simple but as far as i could see i had to re-make the circuit. Going to bleed and re-fill the system tomorrow so I guess time will tell......

My bongo has been running without a stat fro a few thousand miles. The body of the stat is still there so it is sealed.

Yes, when I took my old one out a couple of months back I think I threw it. Wish I hadn't now as I could have done the same thing as you...

[haydn callow]

Going by your remarjks above...It sounds as though it could well be the stat...If you put it in boiling water it should always open...I would just put a new one in.

[missfixit70]

Quote:
You don't need to join the pipes IMO, just block the feed & return to the heater matrix as discussed on the thread I linked to, I'm thinking of going back to this idea



I must admit I don't understand why you don't need to join the pipes? I by-passed mine this morning and it was quite simple but as far as i could see i had to re-make the circuit. Going to bleed and re-fill the system tomorrow so I guess time will tell......

Because the rear heater is an add on circuit to the basic cooling system that is effectively a by pass IMO.

Agree with Haydn re the stat if it only works intermittently when you test it out of the engine, how can you trust it to do it's job in situ?

[Aunt Trumpet]

Going by your remarjks above...It sounds as though it could well be the stat...If you put it in boiling water it should always open...I would just put a new one in.

Agree with Haydn re the stat if it only works intermittently when you test it out of the engine, how can you trust it to do it's job in situ?

I phoned the motor factors I bought it from and they said that because it was a ANG? part it was guaranteed and almost like a genuine part and in order to get an exchange I would have to send it back for testing. If it was found to be faulty I would get a refund, but it could take 3-4 weeks!!
In light of this and the fact that I got it to work 4 times after the initial "fail" I decided to put it back in and give it another chance.
A mechanic mate came round today to give me a hand with the re-fill and bleeding and the symptoms are the same... .....we got it up to temperature and the fans come on, bled the system but still the bottom hose is cool to touch!! We took it for a run and it started to overheat, so we stopped and released the pressure from the bleed pipe and nursed it back. The bottom hose was still cool.

When we got back on the drive I felt all around the stat and the hoses above the stat are hot but beneath it and running to the bottom of the rad are cool....any ideas? Which way does the coolant flow? through the top of the stat housing to the bottom hose or from the bottom hose up?

What else could possibly cause this section to remain cool if not the stat?.....
My mate reckons that it pressurised quite quickly on the short journey back to the drive and that points to head gasket failure..

So, the upshot is that I'm going to flush the rad through on Thursday morning to satisfy myself its not a blocked rad and he's brining over a head gasket tester for a final diagnosis.....I don't think much of my chances to be honest...any other ideas or thoughts folks??

Any help much appreciated...