bodilx6 Posted October 10, 2011 Share Posted October 10, 2011 When I started the car up yesterday, I had a strange but very noticable gurgleing sound from behind the firewall. It kind of reminds me of the sound when my old MK3 had a knackered head gasket. In the last few weeks I've also noticed a comparable sound when the engine passes 2-3k revs while driving normally, but thats just for an instant at a certain rev. I've just changed oil and that looked very nice and normal. I don't see any white stuff in the oil, and knowing the head gasket is not a normal failure in the MKIV I don't think that is it. The car is BPU and has 100.000 miles on it. If I take the rad cover off and massage the coolant hose, it seems that it system is fully topped up. I dont have irregular idle (which I've noticed is typical after changing coolant due to air pockets) and all seems well temperature wise. I have not leaks. Any idea what to check? Quote Link to comment Share on other sites More sharing options...
imi Posted October 10, 2011 Share Posted October 10, 2011 Sounds like an Air lock, perhaps bleed the system to be absolutely sure Quote Link to comment Share on other sites More sharing options...
Dnk Posted October 10, 2011 Share Posted October 10, 2011 When the system is cold is the rad full, i assume the expansion tank is half full. Is your heater still blowing nice hot air ? Quote Link to comment Share on other sites More sharing options...
Havard Posted October 10, 2011 Share Posted October 10, 2011 You may have an air lock in the top pipes just before the bulk head. I had this on my NA and modifed the pipework so that I would top it up from a connection at the back. I only filled it once and never had a problem again. H. Quote Link to comment Share on other sites More sharing options...
bodilx6 Posted October 10, 2011 Author Share Posted October 10, 2011 ok, sounds like airlock is a possible culprit. Wouldn't a possible solution be to park the car on something steep or jack it up in the front and let it run idle with the rad cover off for a bit? Might start off with topping the expasion tank a bit. It is nowhere near half full. Thought that wouldn't matter though. Quote Link to comment Share on other sites More sharing options...
Dnk Posted October 10, 2011 Share Posted October 10, 2011 (edited) Its only a problem when the cars cooling down, air can be drawn back into the system if the coolant level is lower than the pipe inside the tank. As long as the pipe from the cap is in the coolant when its cold it should be okay, i just said half full as its pretty safe then Edited October 10, 2011 by Dnk (see edit history) Quote Link to comment Share on other sites More sharing options...
bodilx6 Posted October 10, 2011 Author Share Posted October 10, 2011 I'll check tonight Quote Link to comment Share on other sites More sharing options...
bigbloodyturbo Posted October 10, 2011 Share Posted October 10, 2011 I had this sound when my HG started to go, pretty soon afterwards it got hard to start and would miss, then one day it drank all its coolant. Quote Link to comment Share on other sites More sharing options...
bodilx6 Posted October 10, 2011 Author Share Posted October 10, 2011 I had this sound when my HG started to go, pretty soon afterwards it got hard to start and would miss, then one day it drank all its coolant. Did you check your oil for contaminents during this? Quote Link to comment Share on other sites More sharing options...
bigbloodyturbo Posted October 12, 2011 Share Posted October 12, 2011 Did you check your oil for contaminents during this? yes, no water was in the oil and initially there was no oil in the water but then the day it started to drink coolant I had the coolant checked and it was positive for hydrocarbons. Turns out it was blowing between cylinder and water jacket. Quote Link to comment Share on other sites More sharing options...
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