I have a 1990 NA Fairlady and was involved in a small prang late last year. Insurance fixed the visible damage but after a couple weeks i noticed this noise from under the bonnet. The water/coolant in the reservoir filling point was boiling/bubling. I also noticed that water is leaking after i drive the car. There are no visible areas where the water is leaking and i have had 2 pressure tests performed but they dont show anything. Insurance company has suggested a mechanic to pull out the radiator to perform a pressure test with the radiator out of the car (this is going to happen next week). Does anyone have any ideas whether this is a radiator problem or something else ( i had replaced my water pump 10,000km ago when i performed the 100k service). Any help would be appreciated.
have you tested the cap? to get bubbles in the reservoir it must be getting past the cap. either the cap is not holding pressure or the coolant is getting too hot. flashing off.
2nded ... also is the cooling system completely full? Low coolant = overheating = boiling water. If a non zed repairer refilled the radiator (I take it the accident involved the rad area?) they may not have known about the burping process...
Expansion tank damage perhaps? Was the accident damage to front left? It is possible your expansion tank (reservoir) is damaged and leaking. The 'bubbling' may be coolant entering the expansion tank as your engine heats & the coolant is forced out from the radiator - quite normal. You may only be hearing this bubbling if the expansion tank is low or nearly empty due to damage. Check the hose from rad to exp. tank, it could also be damaged or crimped.
i agree that it is normal for water to get by the radiator cap and into the expansion tank or reservoir. but not at low/no pressure. if the water is not subjected to some compression then it will boil at normal temp and pressure. the reservoir is at atmospheric pressure due to its overflow. 1 get the cap tested, couple of seconds to test. if ok. 2 subject the cooling system to working pressure, with a cooling system pressure tester.(can usually test the cap with these instruments, most mechanics have got one, i am not a automotive engineer however i have one).if ok. 3 change coolant and insure there is correct amount of additive usually glycol. if ok. 4 check radiator, reverse flush.if ok. 5 check cylinders, bubbles in radiator when running, oil emulsification etc. i hope for your sake you don't have to get this far.if ok 6 check timing. if ok. 7 ask someone else. 8 what have i forgotten. hope there is some assistance here.
Johno: I think you're misreading the posts.... If you check Serge_ZX's post - he's had the system pressure tested TWICE! Coolant 'overflows' from the rad via the cap as temps (& pressure) increase & coolant expands - which is why cars have an expansion tank. Again, check the original post - it appears heat-soak may be causing the overflow and thus Serge_ZX is seeing the 'leak' & hearing 'bubbling'. NOTE: Ppl often make the mistake of topping up the rad instead of checking the expansion tank level (cold). This may also produce the symptom described as it eventually causes the expansion tank to overfill & leak!
I get the same bubbling On a hot day (say 32-33 deg or hotter), once I stop the engine and the latent heat from the engine is absorbed into the coolant, I can hear boiling / bubbling past the radiator cap into the expansion tank. If I press down with my finger onto the radiator cap it stops. I am only using a 0.9 bar cap, as I am worried a 1.2 bar cap might stress my hoses too much. Whenever I check my radiator fluid levels, they are always OK, so fluid seems to be passing back and forth between the radiator and expansion tank as it needs to. I am not too concerned, I have a TWD courtesy of Rob [K-ZED], which will serve as an early warning device.
i have noticed water dripping from..... under the left manifold (somewhere in this region). i only noticed this today after i tried to search for water leaks on/around the radiator. any clues Rob?
Re: Water dripping ... Are you sure it's coolant, not a/c condensation? If coolant is the drip viewed from above or below? If below, is it running off the splashguard... could be coming from anywhere. If above then it could be either from under-plenum or LH turb cooling hose/pipes.
Check the water but this may be condensation off the Air Conditioner pipes and unit. You can tell if its coolant as it will stink and be greenish where as condensation off the A/c will be clear. MattB
the drip can be heard but not seen...... i could see the drip accumulate underneath the car. i can hear it drip onto the hot metal surface near the manifold and sizzle. it may be the air con condensation. i have booked the car in on monday nite and will find out if the radiator is effected. also one last question, if the radiator top-up tank dip stick reads between Cold and Hot (therefore adequate water in radiator) but when you open the radiator cap and look down into the radiator and there isnt any water is this normal??? Any commnets would be appreciated.
Interesting? No, not necessarily 'normal', but at what stage/time/temp are you checking the rad level? If the engine has cooled overnight the rad should have coolant visible approx. 1" below cap, although due to the 'bend' it may require real close inspection. Have you, since yr first post, topped up the rad or expansion tank? Good idea to book in to a mechanic & have it checked thoroughly.
it is empty.... when the car is cool (overnight) but reads fine on the dipstick. and yes i have topped it up with water....i have stopped using coolant as it is costing me a fortune. I will find out next week what the root cause is (thats if the mechanic figures it out). would the water pump be causing the bubbling noise i am experiencing?
If you think it's too expensive using coolant, Wait till>>> you get the quote for fixing an engine that hasn't been having coolant used in it. That should really "curl your toes".:thumbsdown: Maybe you should buy an early VW (no coolant at all!):LOL::LOL::LOL::LOL:
If you are topping up via the radiator cap and the level keeps dropping then you definately have a leak. The purpose of the overflow tank (OT) is to vent excess pressure and hence a bit of coolant into the OT. When the engine cools it sucks coolant back from the OT. This is why the OT dipstick reads different levels when hot & cold. My guess is that the bubbling in your OT is steam from low coolant level in your system. If your system has a leak it is unlikely to be able to suck fluid back into the radiator from the OT. A pressure test of the system is quick to show good or leaking. Finding the source of the leak may not be so easy. Good luck. Cheers, Dean
if you check the cooling system when it has been driven if there is no pressure in the top hose it indicates that there is a leak. If thats the case you will definatly have a leak and therefore the expansion tank will never refil as air will ingress easier than the suction process which normally happens in a proper system in tip top condition. BTW I,m with chili always use coolant and the same brand as coctail mixes are a no no.
