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Discussion Starter #1
i have had problems with my water blowing out the tank after a while of driving .
today i noticed the lower rad hose is cold after coming off the motorway for 100 miles ,
i think these are the symptoms of a blocked rad or broken stat . would this be correct as to my symptoms ?
i think i am on the right track
kieran
 

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Discussion Starter #4
im going to change the stat tomoz . the engine had a top end rebuild not so long ago and new water pump and belts . also no sign of water in the oil if that helps . and it does not show overheating on the dash . and yes my heater works ok
 

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Discussion Starter #5
flushed system out and changed stat , i now have full flow as the bottom pipe now warms up . i have flow back to the header tank so the pump must be working ? but its still pressurizing . i also put some steel seal in it but no good !!
i think i used the steel seal correct , if you read the instructions does it say you are to run the cooling system with steel seal only in it for 1 hour on tickover or is it mixed with the coolant . i did the latter , would it not overheat with just the steel seal in it as the instructions indicate ?
 

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I Dont whant to panic you mate, but when I had the same problem of cooloant blowing out of the header tank, ie. it was over pressurising, it turned out to be a CRACKED HEAD. Hopfefully this is not the case for you.
 

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I Dont whant to panic you mate, but when I had the same problem of cooloant blowing out of the header tank, ie. it was over pressurising, it turned out to be a CRACKED HEAD. Hopfefully this is not the case for you.
yeah , i think its either a cracked head or gasket has gone caput !! oh well , looks like yet another thing that the AA will have to pay to put right :ILU:
 

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I had/have this bottom pipe being cold problem. I've fitted three replacement thermostats and none of them are opening.

The temp gauge goes up to 90 and stays there. It doesn't overheat or leak. With a thermostat in it uses water, without a thermostat it uses no water.

I have no blocks in the cooling circuit anywhere, no oily/watery issues either. I get heat through the heaters with or without the thermostat (granted it takes longer to get warm without).

I'm currently running with the rad covered with foil and an aluminium plate to stop overcooling.

My problem comes down to the thermostats won't open. When i tested them they only opened when in boiling water in a pan on the hob. Not even boiling water from the kettle would open them. Engines don't run at boiling point so i'm totally confused over it. :*
 

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Discussion Starter #9
I had/have this bottom pipe being cold problem. I've fitted three replacement thermostats and none of them are opening.

The temp gauge goes up to 90 and stays there. It doesn't overheat or leak. With a thermostat in it uses water, without a thermostat it uses no water.

I have no blocks in the cooling circuit anywhere, no oily/watery issues either. I get heat through the heaters with or without the thermostat (granted it takes longer to get warm without).

I'm currently running with the rad covered with foil and an aluminium plate to stop overcooling.

My problem comes down to the thermostats won't open. When i tested them they only opened when in boiling water in a pan on the hob. Not even boiling water from the kettle would open them. Engines don't run at boiling point so i'm totally confused over it. :*
i did read your post on this , i think i may aswell try removing the stat and see what happens T: . i only need the van now long enough to find a new one so dont want to be spending any money on it to be honest !
 

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Nope still running without a stat for the moment. However what i have noticed without the stat is that there is only full circulation when running above idle revs. I don't know if this is how it should be or if the water pump is just good enough anymore.

I would have thought the water should be ok as it was changed when i did the belts 2 years ago.
 

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I know this is an old thread, but got the same symptoms here and wondered how you got on with it?

I have recently changed the thermostat, water pump and coolant, i noticed the van takes a little while to heat up, then a few coolant runs down the back of the expansion tank.

I have fitted a new tank cap, not genuine though. No water loss, no unusual smoke, no over heating, heaters get hot fine, temp doesnt drop, but the bottom coolant oipe is cooler than i would expect, is the rad just very god at its job? Cant explain the couple of dribbles of coolant from the tank? Faulty and leaking when accelerating?

Unless as stated the bottom hose will feel cooler when idling?
 

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I know this is an old thread, but got the same symptoms here and wondered how you got on with it?

I have recently changed the thermostat, water pump and coolant, i noticed the van takes a little while to heat up, then a few coolant runs down the back of the expansion tank.

I have fitted a new tank cap, not genuine though. No water loss, no unusual smoke, no over heating, heaters get hot fine, temp doesnt drop, but the bottom coolant oipe is cooler than i would expect, is the rad just very god at its job? Cant explain the couple of dribbles of coolant from the tank? Faulty and leaking when accelerating?

Unless as stated the bottom hose will feel cooler when idling?
I wonder whether we are all shooting ourselves in the foot here.

My bottom hose is cold so basically I've changed everything & it's still the same!!! there are no faults, everything works fine ~ the stat opens fully at 102 degrees ~ my van never gets beyong 90 !! :cool:
 

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Hhmm, anyone got a warm/hot bottom hose?

I have read that there can be air caught in the rad after a coolant change, i didnt bleed mine for too long so may give the bottom hose a good squeeze when up to temp with the expansion cap off and see what i can get out, if anything. I flushed it all when i changed everything.

Do you have any runs of dried coolant from the back of the expansion tank?
 

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Your lower hose should be cooler than the top hose as thats what the rad does cool the coolant.

Hot coolant goes in the top of the rad as it cools down in the rad itll drop downe in the rad and out of the lower hose... the pressure you aare experiencing could be diwn to a faulty header tank cap.... the system should be under pressure or else it'll boil and wont cool your engine.

To check for a blocked rad when engine is cold drop hoses top and bottom on rad and flush rad through from the top top to bottom with a hose pipe it should come out slightly slowr at the bottom but a good flow.

To check a thermostat you need tohang it in a pan of cold water so its not touching the sides of the pan and is fully submerged in water, using a thermometer raise the temperature of the water until it opens then check the thermometer ti see what temperature its opening at...

Dave
 

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I understand the coolant should come out cooler, but on a stationary vehicle ie. No winding cooling the rad, i expected the bottom hose to be at least warm. My cars bottom hose runs fairly warm, so was surprised when i felt it.

I have pressure when hot and none when cold so all seems well and may well be running as it should i just wasnt sure.
 

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I gave the bottom hose a good pump and low and behold it heated up, just air caught in the rad it seems. Gets nice and hot now, not as hot as the top one, but as hot as i have been used to with all other vehicles i have owned. The van now heats up quicker too.

Worth a look for sure.
 

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I wonder whether we are all shooting ourselves in the foot here.

My bottom hose is cold so basically I've changed everything & it's still the same!!! there are no faults, everything works fine ~ the stat opens fully at 102 degrees ~ my van never gets beyong 90 !! :cool:
After a recent oil change, I thought my engine bay and cab vents felt hotter than normal. I was getting a bit worried and thought the fans weren't kicking in, so installed a new fan temp sensor + thermostat. After refilling system, cab heater worked but bottom pipe still stayed cold and no fans (even once gauge was up to 90 deg). I noticed the radiator was still cold and was about to re-drain system thinking I had an air lock, but when I squeezed the radiator in/out pipes I could feel the coolant moving. Decided to leave the van ticking over for about half an hour and eventually the radiator & bottom pipe became hot. Connected up my vagcom (best £15 ever spent on eBay) and hey ho, van was sitting at 91 deg (gauge is bang on). Revved for a bit till temp rose to 95 deg and fans kicked in A: I can only conclude as hobbyhorse, that it takes a bit to get my van above 90 deg.

Decided to stick the old thermostat and sensor in a pan of boiling water to see if they worked. Thermostat opened and sensor produced a short across the contacts, so looks like I wasted a day and £60 :(
 

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I do think that it just takes a while to heat up, I still check my rad pipes every now and then and it does seem to need a while to get the bottom hose heated up to any kind of temperature. So just put it down to an efficient system.
 

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For many many years my temp gauge didn't show any desire to move until I'd done at least 5 miles (20 mins london suburb driving).

So I've always assumed the warm up time is just slow

Don't know what happened but one day last year I noticed the gauge woke up much earlier, more like 2.5 miles. I'd not done anything to it for some time and its stayed that way since.

Cannot comment on hose temps.

2.5 ACV Tdi, 90,000 miles, one owner.
 
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