Fetch me a tank!
Discussion
In the course of fitting my new rad, I've been having problems with bleeding the system. After leaving it a couple of days I've tried again today and think I've discovered why I've been having problems.
Got the temp up to around 80ish degrees, there was smoke/steam coming from around the expansion tank/battery the whole time the engine was running. I thought this was just a bit of coolant I'd spilled when filling the tank, but when it started to get worse I noticed the coolant was dripping from the underside of the tank, right in the very middle (see pic - not my tank - borrowed pic from pmessling topic).
Before I go and order a new tank, I just wanted to have a sanity check (poorly dog over the weekend means I'm very, very tired right now). There is no reason, other than a split tank, that coolant should be pi$$ing out of the bottom of the tank, at 80 degrees C or less?!
Got the temp up to around 80ish degrees, there was smoke/steam coming from around the expansion tank/battery the whole time the engine was running. I thought this was just a bit of coolant I'd spilled when filling the tank, but when it started to get worse I noticed the coolant was dripping from the underside of the tank, right in the very middle (see pic - not my tank - borrowed pic from pmessling topic).
Before I go and order a new tank, I just wanted to have a sanity check (poorly dog over the weekend means I'm very, very tired right now). There is no reason, other than a split tank, that coolant should be pi$$ing out of the bottom of the tank, at 80 degrees C or less?!
Sadly that is exactly what is supposed to happen!!!
I know, it is insanely stupid, that is why the passenger side upper chassis rail fares so poorly.
I have just about managed to shove an appropriately sized hose up in to the central overflow hole, but it doesn't really work, because when the cap vents the volume is too great for the hose (as I discovered yesterday when my fans decided to die in gridlocked JFK Boulevard Luxembourg).
I know, it is insanely stupid, that is why the passenger side upper chassis rail fares so poorly.
I have just about managed to shove an appropriately sized hose up in to the central overflow hole, but it doesn't really work, because when the cap vents the volume is too great for the hose (as I discovered yesterday when my fans decided to die in gridlocked JFK Boulevard Luxembourg).
There is no reason, other than a split tank, that coolant should be pi$$ing out of the bottom of the tank, at 80 degrees C or less?!
If you are sure you are not over filling the expansion tank, then could this be a head gasket issue? Cylinder gasses passing the head gasket into the cooling system and over pressurising the cooling system and relieving through the next weakest point. Being the expansion tank cap!
You said you have just put a new radiator in, did the old one sping a leak perchance, this could support this theory, (old rad burst due to being over pressurised?)
Sorry to be a complete pessimist,
If you are sure you are not over filling the expansion tank, then could this be a head gasket issue? Cylinder gasses passing the head gasket into the cooling system and over pressurising the cooling system and relieving through the next weakest point. Being the expansion tank cap!
You said you have just put a new radiator in, did the old one sping a leak perchance, this could support this theory, (old rad burst due to being over pressurised?)
Sorry to be a complete pessimist,
Possible I guess, though I've not noticed any other symptoms of a head gasket failure, engine pulls like a train and is generally quite smooth.
I think I'll fit the new tank when it arrives tomorrow (as it'll be nice and clean plastic anyway), maybe go back to the old cap too and see how things go. From what I remember when I changed the hoses over to silicon, the expansion tank isn't too hard to remove.
I think I'll fit the new tank when it arrives tomorrow (as it'll be nice and clean plastic anyway), maybe go back to the old cap too and see how things go. From what I remember when I changed the hoses over to silicon, the expansion tank isn't too hard to remove.
I see what Paul (ukkid) was saying now! The cap vents on to the top of the tank, but I believe the idea is that it is collected underneath the teardrop shaped plastic cover, which then flows through to this central overflow pipe on the underside. I guess on the Audi (which the tank is originally from), they have a hose connected to this overflow pipe so the coolant doesn't piss all over the exhaust and battery! 
So I think it's looking less like that my tank is split and probably something else. Dear god I hope my new cap is faulty!
So I think it's looking less like that my tank is split and probably something else. Dear god I hope my new cap is faulty!
Got to 92 degrees this time! Did seem to be better with the old cap on, but maybe that's just me hoping it is.
I've changed the fan plugs over to AMP Superseal weatherproof connectors, though I don't think the fan kicked in (it only just touched the temp needed to kick in Fan 1), so need to try and get it up to temp again.
Did seem to be better with the old cap on, but maybe that's just me hoping it is.I've changed the fan plugs over to AMP Superseal weatherproof connectors, though I don't think the fan kicked in (it only just touched the temp needed to kick in Fan 1), so need to try and get it up to temp again.
Success!
Ran for over 10 minutes with no volcano like eruption out of the expansion tank. Seems it was likely just a case of overfilling, I suppose with the new rad on there, the "natural" level of the coolant is now lower than what it was.
Also didn't help that one of the AMP connectors wasn't quite holding a wire, so Fan 1 wasn't coming on. Have swapped out with bullet connectors for the time being.
Ran for over 10 minutes with no volcano like eruption out of the expansion tank. Seems it was likely just a case of overfilling, I suppose with the new rad on there, the "natural" level of the coolant is now lower than what it was.
Also didn't help that one of the AMP connectors wasn't quite holding a wire, so Fan 1 wasn't coming on. Have swapped out with bullet connectors for the time being.
Only had my Cerb ('97 4.2) two months, but one of the first things Jason at Str8six told me (when I took it to them to have a couple of issues sorted out) is that you should keep the level of coolant in the expansion tank low - if you fill it to the line it will frequently come over the top. Mine is about 3cm below the line and he said that looked about right.
Just to wrap up this topic. I sold my Cerb not long after making this topic as I strongly suspected head gasket failure and I just didn't have the time to take the engine out of the car (again). Car was sold as such and then new owner found that was exactly the case once the engine was stripped down.
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