Hi all,

 

Before I get my Zed back (new autobox and converter) this weekend should I get the garage to investigate a bubbling sound I get from the middle/back of the engine.

 

 

When I return from a run after the engine has warmed up I can hear the bubbling sound, dont know if it is an air lock because I have had a new rad on in Devember, it did it befor and it still does it now. We even had the car on a slope with the heaters on full blast when we did the radiator change.

 

When I check the water levels (rad cap) after the engine has cooled down it is still full to the brim so hopfully not cylinder head gasket failure, although I am no expert.

 

Anybody got a similar sound or know what it could be?? :confused:

Um, I would say yes!!!! get them to check it out! Something is overheating somewhere and thats never good!

You sure it's not coming from behind the wings? If it is, then

it's the AIV's & isn't a problem. Otherwise, yes get it checked!

Could it be that my Rad cap is only rated to 0.9 bar or psi or whatever and not 1.2. Actually what should it be?

Coming from under your wing easy to cure.

I did ask a mechanic about it a while ago and he said it was doing it beacause zed engines run at such a high teperature with not much air flow around the engine bay. Dont know if he is any good though.

 

I have heard that it could be the AIV's is that right for the valves in the wings. Still think it is from the back in the middle, I will chech when I get her back.

could be air in the system this causes a bubling fron the engine when it gets hot.

Im willing to bet its a hose thats perished at the rear of the engine bay, once you put a new rad on it tends to make all the perished or weak hoses blow, alot of the time they dont appear to leak as they suck air and leak a bit when on the move, then the air bubbles out about 30 secs after shut off.

 

A good way to see if the system is losing pressure is by squeezing the rad top hose, this should be quite well pressurised for a good while after a drive.

 

My bet is the 2 matrix hoses, or one of the plenum to tubby pipes.

 

Good luck.

Thanks for that.

 

Are the 2 heater matrix hoses the two that are next to each other right at the back of the engine bay in the middle? If so that is the area the noise is coming from.

Might check up in the on line manual. Cheers.

i get exactly the same noise but not after every run so im now going to go check my car over again as i can hear it but see nothing to resemble water from the engine

Hi z evo guy,

 

If you do sus send me a PM please.

 

Am going to get all my water pipes renewed, so hopfully that will cure it!

Check all your hoses.

Most of the hoses are now 15 years old as they are not the usual things people replace unless they split. They do get weaker and not able to hold the water pressure in.

This is why I dont like the idea of higer rated rad caps. Yes in theory they should make the water cooler because of the pressure, but the hoses when stock where not designed to hold that pressure let alone after 15 years of use.

Good advice SRRAE so the 0.9 rated cap should be OK?

 

Am going to get a set of new hoses fitted, anybody know where the best place to get them is?

Im willing to bet its a hose thats perished at the rear of the engine bay, once you put a new rad on it tends to make all the perished or weak hoses blow, alot of the time they dont appear to leak as they suck air and leak a bit when on the move, then the air bubbles out about 30 secs after shut off.

 

A good way to see if the system is losing pressure is by squeezing the rad top hose, this should be quite well pressurised for a good while after a drive.

 

My bet is the 2 matrix hoses, or one of the plenum to tubby pipes.

 

Good luck.

 

 

Had similar prob/sound two weeks ago, then after a futher week developed a hissing sound from same area, followed by a coolant leak, and indeed 1 pipes had perished, so replaced them all while back there, ordered from Nissan, and problem sorted...

Hope this is the case for you too! :)

Hi 2-up.

 

Thanks for that I hope it is the same for me.

 

By the way how much did Nissan charge for the new pipes if you dont mind me asking?

Hi 2-up.

 

Thanks for that I hope it is the same for me.

 

By the way how much did Nissan charge for the new pipes if you dont mind me asking?

 

 

£15 each for the heater matrix pipes, and replaced the others with 8mm hoses bought from local car parts shop as they were just straight pipes, hope all goes well, and if you doing it yourself be prepared to lose a little skin from your knuckles...All the best mate. :D

check the seal around the radiator cap and if it seems easy to screw on id recomend getting a nissan OEM rad cap rated at 1.2 bar try the cheapest 1st

 

as said check pipes that run from under plenum to turbos

 

and matrix hoses could just need the jubilee clips tightened if not for the sake of £15 each get them replaced

 

a good sign to see for leaks over long periods is looking around engine bay and see for any hot water limscale marks on top of turbo housing,bellhousing around the front of the engine,once narrowed down it makes life easier

 

good luck

Thanks for the advice boys, looks like I'll be busy next weekend!

Thanks for the advice boys, looks like I'll be busy next weekend!

 

 

Girlie here...LoL, Should have gone with a more obvious name really... :D

Sorry 2-up.

 

But when I think about it, what a great name!!!

No worries...LOL

 

:D :D

it turned out to be a blockage in the coolant line running to the left hand turbo.. my symptoms were the left hand side of the plenum running cooler than the right, the coolant was boiling in the heater intake (you could feel the coolant boiling at the hose). The blockage had also caused the hose from the turbo to the heater intake at the back of the engine to blow, not much fun to replace.

 

I disconnected the heater intake and the coolant line to the turbo from the front left of the engine, hooked up a foot pump and a small plastic bag popped out. :) dunno what the hell that was doing there but I can imagine that with the angles of some of these hard pipes, they could block through corrosion etc pretty easy too.

I may well have had a blocked turbo coolant line but the boiling did return.. Actually I thought I found the problem a few times but I think I finally know the reason for it.

 

I didn't have an ECU bracket until a few weeks ago, I also hadn't boiled for a while until today when I went out after messing with the ECU and didn't bolt it back up. It was just a short trip on a cool day with no boosting and yet when I switched off, I heard boiling at the back of the engine. This just 2 days after I made a long trip on a very hot day using A/C and occasionally boosting but without boiling.

 

I don't know the exact cause but you might want to check your ECU case is properly earthed.. Hopefully we can determine that this isn't just freaky coincidence.