A&Q about 350Z
Q:
Hey Guys,
My car has had its 3rd set (all from the scappy) of heater bypass valves, and I was thinking of buying some brand new from eurocar parts or gsf. But I have found the price difference of the bypass valves and a new matrix is £5. So im thinking of buying a new matrix and fitting it in over a weekend.
However my headgasket needs doing (for the 1st time), and well as all the other things that need replacing for a car thats done over 130k miles.
Im really confused, do I get the bypass valves and get the heating to work, or replace the matrix and slowly get the headgasket etc done. Its only a 1.6 CL but its been in my family since 1990.
Also does anyone have a rough idea how much it would cost to do the headgasket and clean the bottom end.
Regards, Pritesh
A:
If there isn't a problem with the matrix just bin the bypass valve. My '91 Mk2 never got one fitted and is just fine. The bypass was fitted as a panic measure after a couple of matrix burst, it is the weakest link in the system if it over pressurises.
If the headgasket is failing and so pressurising the cooling system even a new bypass valve won't get you any heat as it will be doing what it is supposed to do. You need to bite the bullet and get the headgasket changed before doing anything else, and hope the matrix is fine as they're buried in the dash and so a right job to change.
Barkstar
A:
Also something that im considering doing. I read in some previous posts after doing some searching, that replacing the bypass valve with a pipe can cause the matrix to burst! Is that actually the case and how can I check if my matrix is not up to scratch?
Thanks
A:
Yeh I dont know whether my matrix is up to scratch. Some people here have had their matrix burst even with the valves installed.
Thanks Barkstar, I guess I had better get my headgasket done. I have been dreading it, along with the waterpump, oil pump etc.
A:
Also something that im considering doing. I read in some previous posts after doing some searching, that replacing the bypass valve with a pipe can cause the matrix to burst! Is that actually the case and how can I check if my matrix is not up to scratch?
Thanks
IIRC there were only a handful of cases of burst matrix and they will only burst if the system is over presurising due to another fault. VW decided to take no chances and beefed up the matrix on the Mk3 - did I read that it will retro fit the mk2? The matrix is fine in normal use, it just the weakest component in the whole system if there's a failure.
If what you said were true then how come my Mk2, which never went in for the recall, hasn't poached my feet? The bypass valve is presure sensitive and diverts the water away from the matrix if the system has a fault (like a failing headgasket). Over time they corrode internally and seem to most often fail safe - so no heater. Lots of others have binned them, and used plain pipe and I won't be fitting one anytime soon.
I don't recall seeing any thread where a matrix has burst suddenly, though quite a few have started leaking due to old age.
Barkstar
A:
Ok cool, so more than likley I wont have any problems just sticking a pipe in the valves place.
If I post up a pic later of me pointing at what I think is the valve, could someone tell me if I'm right or wrong.
Thanks
(Sorry for jacking your thread muppet9966 )
A:
Hi
Looking forward to the picture.
A:
Ok could someone tell me which one it is.
Thanks again.
A:
Anyone?
A:
I'll have a look when its daylight but I can only tell you what yours has that mine ain't - But I can't picture A under the bonnet on mine.
Barkstar
A:
Ok cheers :)
A:
itsdiagram A. i had the matrix expload on the way home from when i brougth the car and it not very nice. if i was you i would buy brand new valves from vw at £32 but if you have no joy with that then reverse flush the matrix system or just buy a brand new matrix it is deffently not worth fitting a second hand one
A:
interested in this thread as my heating is well below par,and think the same valve is doin me a dis-service ,if you by-pass the valve pictured 'a' where does the ickle pipe beside it go then ??
A:
Ok thanks grump, I shall take a trip to GSF before the weather gets too cold
A:
im not certain on this but i think you just put a copper pipe in the to pipes on the left so the right one is not used (from diagram A) but you will have to check that but like i say it is not worth the trouble risking your matrix.
A:
Just out of interest, could I take the valve off and clean it out? Would that make any difference?
Thanks again
WM
A:
Iv Tried That A Few Times And It Has Never Worked.
A:
Replace both valves with copper piping. If that sorts the issue I'd leave it at that! I've had the bypass valves removed from my GTI for god knows how long, and all I've got is lots of heat
A:
Im thinking of replacing my valves with copper pipes, but I dont know whether my failing headgasket will put strain on the matrix. The back of my engine is oily, looks fresh so I think its the oil leaking out of the engine, and im losing abit of water and oil, not that much though.
A:
More likly to be rocker cover gasket leaking oil, and other hoses/flanges leaking your coolant. If the head gasket had gone between a bore & a waterway you would know about it!
A:
Rubjonny's right. What symptoms have you got to suggest the gasket is failing? When it went on my Mk1 Gti I just got oil in the coolant - the car ran just fine. If it fails between a cylinder and a waterway you'll get clouds of steam and be pushing lots of pressure into the coolant system.
BTW as I thought I haven't got an A, the B appears to be the junction to the heated inlet manifold.
Barkstar
A:
Well the only symptom the car has is oil at the back of the engine. However last year I did do the rocker cover gasket, and then the alternator had to be changed, and the bolt holding the alternator became rounded, so I had to remove the timing belt cover, two of these nuts also hold the rocker cover, and I forgot to put them back on when I started the car, and then I drove about 2mile. Oil was everywhere, I still havent changed the rocker cover gasket again. Could this be leaking? I think the water leak is from the right hand side of the engine block, above the gearbox.
A:
Iv Tried That A Few Times And It Has Never Worked.
Hi
What could you see inside the 3 pipes valve? Did you try cleaning it with a kettle descaler or what ?
Cheers for the info.
A:
After freezing through four winters, I got the by-pass valves changed in mine. Result? Heat for about twenty miles, then it cut out again. Two years ago, replaced the valves with copper pipe and had lovely warmth ever since.
I believe someone did post a photo on here once of his blistered toes where his matrix had burst, he's the only person I've ever heard of ever who was unfortunate.
But the ultra-cautious ex-VW technician who took my valve out for me said that there'd be warning signs, such as steam in the car, before the matrix burst. So that may be good warning before you got poached toes! Definitely worth the gamble, instead of driving round frozen all the winter months!
A:
Oil was everywhere, I still havent changed the rocker cover gasket again. Could this be leaking? I think the water leak is from the right hand side of the engine block, above the gearbox.
Did you use one of those dreadful cork gaskets? Once they leak there's no stopping them.
VW do a rubber gasket but you need to change the studs - though they come with the gasket if you get the kit, just explain what you're after, my dealer's parts man knew the number off the top of his head. You also often get a weep between the head and block at the back at the cambelt end. As long as it's just weeping it. not a problem.
And I'll bet your water leak is the plastic flange on the end of the head. It'll have cracked or the o ring will have died. Few quid from VW, I think it comes with the o ring. Give the threads in the head a careful clean out, if you strip one it'll never seal and you'll need the head off to fix it properly - not that I've ever done that
Still in doubt? Get a compression test done, that'll tell you a lot about your engines condition
Barkstar