Help needed regarding cooling!

[herisites 0]

I dont like to start new topics as i usually find enough on the forum and i have found lots of information already but i still feel as though i need to ask for MY situation rather than other peoples as im in the dark to whats happening!!

 

Basically my heater matrix blew last week, i replaced it at the weekend and now i have just flushed the entire coolant from the car by running a hose pipe in the expansion tank whilst the engine is idling until it runs clear. Then filled it with about 2.5 litres of G12+ coolant followed by water and let the engine idle to let air bubbles out of it. I have the heaters on inside the car as well.

 

I ran the engine and loads of bubbles were coming out, then they slowed down to only the odd bubble. I let it run until the engine reached about 90 degrees so the stat would open, now this is where things puzzle me! If the stat is opening at this point the bottom rad hose is supposed to get hot and the water level in the expansion tank drops, correct? Well my expansion tank overflows! Does this indicate that the thermostat is not opening?? Im guessing i need to take the bastard out and chuck it in a bowl of boiling water to test if its opening and if not its new stat time! Although from reading it appears i do not use a new stat from vw as these dont open enough?? I also read about the lower temp stats you can get from awesome gti etc which open at 70 degrees keeping the engine much cooler, would this be a good idea for when i supercharge my car as i wont be running any additional cooling?

 

Also i have been worried about the aux water pump not working. When the engine was hot i felt all the pipes and most (bar the bottom rad hose) were really hot. One of the hoses going to my nice new heater matrix (one on the left as you look in the engine bay) was hot but the other (connected to the aux pump) was not. Could this suggest its seized? I also checked the fuses on top of the controller but these have not blown.

 

And i also need to sort my fans out as i dont think they come on at fan speed 1 but i think i can resolve this from the search, its just the above im stuck with and couldnt really find much help using the search.

 

Much love!

[steve @ 0]

Did you fill from the expansion tank or via the top rad hose? If you used the expansion tank you may well have an air lock. Also there is a bleed valve on the crack pipe. Try bleeding that.

[herisites 0]

Where/what is the crack pipe??

 

EDIT: i filled from the top rad hose until that became quite full then continued filling from the expansion tank.

[Kevin Bacon 5]

Yeah, draining the block is a good idea when doing a coolant change.

 

If you lie under the car, feel up by the oil filter and you'll see a long black plastic pipe. About 6" along from the water pump is a little thumbwheel. This is the block and head drain plug.

 

The method is to drain that, then fill with coolant and water via the rad top hose until water appears in the expansion tank. Run the engine and just as the water starts rising in the tank, screw the cap on, take for a drive, let cool down, top up. Done.

 

The stat opens at 80 deg mate, not 90, and steer clear of 70 deg thermostats. People are obsessed with hot running VRs, but so long as the water is around 95 deg when warm, it's happy. A 70 deg stat may not achieve that in the winter months, which will affect the water temp fuel compensation.

 

If the aux pump is stopped, it won't block flow. Sounds like it could be air lock or stat related.

[Toad 0]

I tend to fill mine as Kev says, run her up with the cap off till it's pretty warm, reving it slightly and occasionally (using the throttle butterfly so you can keep an eye on things) can help to encourage some air out, then put the cap on, let it get up to temp so the fan comes on a couple of times and check for leaks.

 

When the system is running right, the top rad hose will get warm and the pipe leading to the expansion tank will also warm upm you'll see bubbles appearing out of this one. the pipes running to the matrix will get warm quickly too, usually oen before the other but I don't remember in which order, the pipes to the throttle body will also get hot. I've still got my cap off at this point, eventually the bottom hose will warm up as the thermostat opens. remember that this opens slowly, and as the cool water from the rad flows past it, it will close again.

[flyferrari 0]

Hi,

 

Did you ever investigate why your matrix blew in the first place? I would be tempted to get a combustion gas test done on the cooling system to check all is OK with your head gasket. At £20 it can save you chasing round in circles trying to solve your problem. I agree with cheeswire that low temp stats and the like are the work of the devil and tend to mask the real issue by treating the symptoms and not the cause. You also say you are concerned that the hose to the matrix is hot and the return is cold......sound normal if you have the heater on full hot with the fan going......The matrix is a mini radiator after all.

 

Regards

 

Kevin

[herisites 0]

Ok a quick update.

 

I drained the coolant again, this time from the drain plug in the crack pipe as kev mentioned, as well as removing the bottom rad hose. Then connected it back up and added the coolant and topped the water up from the top of the rad and from the expansion tank until it was at max and not going down. Turned the engine on and let it idle for a bit with the odd rev to get rid of bubbles whilst topping up the water level as i went along. Did this until the car got hot and no more bubbles were coming out and as the water level started to raise i stuck the cap back on. All pipes were hot this time, top and bottom rad, and one going into the matrix etc.

 

I then let the car cool down fully and checked the water level, it had dropped but not by a lot so topped it up and took it for a spin. I took it round town for a bit then out on a good stretch of road and gave it a blast, bit of dual carriageway sitting at normal speeds then high speeds and the water temp didnt go over 90 and the oil temp didnt go over 110. I got back and my phone rang so i was chatting quickly with the engine still on, the water temp reached 110 and the fan came on. Then i switched it off and the fan stayed on for a while and went off. I checked the coolant level and it was actually a bit higher than before so im guessing all is well?

[steve @ 0]

That sounds fine to me chap!

[adevr6 0]

had similar issues to you herisites.does your expansion bottle hold pressure when engine is flat cold?points to airlock/leak.mine was seaping coolant when engine cooled down.on investigation the 'O' ring in the thermo housing behind the temp sensor had perished.

[Kevin Bacon 5]

Did you ever investigate why your matrix blew in the first place?

 

Old age mate. The matrix has plastic end cans, which in an enclosed space like the heaterbox is not a particularly clever idea in my opinion. Over the years, the plastic ends and alu radiator expand and contract at different rates and eventually the plastic end cans crack at best, or blow apart at worst. I'd like to see a solid alu replacement, but no such part exists, so we have to live with the prospect of changing the matrix every 8 - 10 years instead, LOL! :lol:

It's amazing how much crap gets in the heater box over the years. When I did mine, the bottom of the heater box was full of wet, smelly leaves and bugs. The leaf guard is there to prevent that, but obviously doesn't work!

 

I would be tempted to get a combustion gas test done on the cooling system to check all is OK with your head gasket.

 

If the gasket is leaking you can smell it in the coolant very easily and it will blow steam out of the tail pipe if leaking bad enough. I doubt he has that issue tbh.

[vwdeviant 0]

I would be tempted to get a combustion gas test done on the cooling system to check all is OK with your head gasket.

 

If the gasket is leaking you can smell it in the coolant very easily and it will blow steam out of the tail pipe if leaking bad enough. I doubt he has that issue tbh.

 

Unless your headgasket does what the one on my Rocket did and fail between cylinders 2&3! No water/oil or steaming exhaust warning... Just driving along and POW down to 2/3 cyls... Garage never seen one before...

 

Good jobs Rob... Rado specialst and detailer is the way forwards for you then! ;)

[herisites 0]

Just to add to this i have driven the car for a few days now since doing it and the coolant level has stayed pretty much the same, but for safe measure i replaced the expansion cap for a lovely new blue one from vw so if there were any air leaks from the old one there shouldnt be anymore!!

 

I dont think that my head gasket is leaking as i have not seen any signs whatsoever, the engine runs sweet as a nut and its done 140k now! Although when i come to put the Rotrex on it im sure i will be testing the head gasket strength :roll: :lol:

 

Jon - I intend to conquer everything there is to do with owning a corrado!! :lol: Its all about Go as well as Show!!

[flyferrari 0]

Wasn't meaning to be a doom monger......just trying to make sure an obvious culprit wasn't overlooked like happened in my case. I expended so much energy and cash chasing the symptoms (with profesionals who missed the signs too) before the real problem came to light. I just didn't want anyone else going through the same s**t. My new engine is being fitted as we speak!!

 

Regards

 

Kevin

[filski 0]

just wanted to check temp levels...

 

when i first got the car last May water temp sat at 90 nearly all day with slight movement. over recent months the average reading went down slowly and so replaced the thermo switches and sensors. Then i saw i was getting high water temps up 110 and 115. So took it in for a look and the old pump was seizing and not pumping so got new pump and thermostat. Got car back, and temp slowly risrs to 100 around town and sits about there. Rises up to 110 and fan kicks in after driving dual carrigeways and sitting in town traffic. not sure how hot is ok..but not seen more than 112ish.

 

as for oil, sits about 100 all day throught town, motoway blasts up to 106/108 generally, and goes abck to 100 in slower driving. But recently did 20 miles on motorway and is went up to 118. came off at junction and it slowly went back down..but is 118 too high..never seem it there before..chacked levels but seems fine. was a hot day but ... what are the 'normal' boundries for running temp??

 

am taking the C over to France next week and will expect hot sunny driving days :) but a bit worried about high temps - what can i expect to be normal and when to start to worring about getting too hot?

 

thanks

[herisites 0]

Ok im going to bump this back up as lastnight i was driving my car home (about a 15 miles journey). Gave it a bit of a thrash on a dual carriageway (bloody clio sports!), slowed down though soon after as he turned off so then just continued about 10 miles down the dual carriageway at about 80-90, then gave it another thrash. When i got home and put the car in the garage i noticed a trail of water following my car, i popped the bonnet and the water level had overflowed the expansion tank! It wasnt overheating, the temp guage was only at about 90-100 max. I left it overnight to cool down and went back down there this morning to check and the water level is still really high!

 

I have checked it and there's no oil in it, there's no smoke/steam coming from anywhere and no 'mayo' etc, so am i right in thinking it could just be an air lock?

[reubenwilliams 0]

OK guys, stupid question but it jumped to mind yesterday when filling my C after replacing pain in the a :!: se water out flange from head because o ring was gunked and weeing water.

 

If you fill from the rad top hose. Wont it all pee out when u lower the hose to attach it back to the engine? or am i talking something of a silly? The big fat rad hose? because mine seems to join to the engine lower down, so when u lower it water will pee out and there will be an air pocket again!! :scratch: This smily pops to mind but he doesnt look confused / simple enough to do this Q justice!

 

thanks

[steve @ 0]

Yeah thats right, it will flow from the top hose but then just top the expansion tank up.

[gogsboy 0]

Yeah, draining the block is a good idea when doing a coolant change.

 

If you lie under the car, feel up by the oil filter and you'll see a long black plastic pipe. About 6" along from the water pump is a little thumbwheel. This is the block and head drain plug.

 

The method is to drain that, then fill with coolant and water via the rad top hose until water appears in the expansion tank. Run the engine and just as the water starts rising in the tank, screw the cap on, take for a drive, let cool down, top up. Done.

 

Does it matter if system been drained and topped up again but when being drained this block and head plug was never touched?

[craigowl 0]

Not 100% sure of what you are worried about, but I would say no. You can drain coolant from any lowish hose, but "crack pipe's" little screw cock :lol: is probably ideal according to manufacturers because it is at lowest point of cooling system.

 

You can flush whole system out with garden hose, too, when you have got most/all of coolant drained off. Try flushing out using a low point then a high point of entry for hose and a fairly strong jet (heater on, too). You will get wet and cold but it is worthwhile. 8)

[gogsboy 0]

Not 100% sure of what you are worried about, but I would say no.

 

Not worried, well suppose I am worried that this head is going or gone but not showing much of the signs.

 

With regards to this, my query was aimed at 'draining the block is a good idea when doing a coolant change' which I took to mean that if you did not drain from the crack pipe then old mix stays in the head/block and I suppose that can't be a good thing, but maybe it doesn't matter at all

[craigowl 0]

Clearly, some old mix can remain if you do not drain from lowest point and also do not flush/backflush system.

Flushing is recommended because sediment and solids will be removed allowing coolant to flow freely and probably preventing blockages later on. I believe passageways in radiator are narrow and can be blocked relatively easily.