PCV valve

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PCV valve

Postby CaptainNorth » Fri Apr 29, 2016 5:15 pm

Just doing a bit of work on my new to me Eunos 1.6. This is our 3rd MX5 and 2nd MK1 and I'm really enjoying the change to the Mk3.

Could a duff PCV valve cause enough pressure in the right place to cause a rocker cover weep?

There's a weep of oil from the LHS of the rocker cover, I've ordered a new gasket and a new PSV valve.

There's also a noise like air being let out of a pinched party balloon (if ya know what I mean?!) around 4250 RPM coming from the general area of the oil leak - escaping gasses/pressure I think.

I guess I'll know once I've changed the valve and gasket.

Sound familiar to anyone?
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Re: PCV valve

Postby OldSpice » Fri Apr 29, 2016 5:27 pm

Not to my knowledge, but certainly if the existing gasket was fitted aftermarket sans the "known" blobs of sealant, that would do it!
Or..perhaps a nasty cheapo not seated correctly.
While you are in there, tbh I'd do the CAS O ring too...their a wee booger to get to.
And....check the heater hoses going into the bulkhead for rotty-poo.

(I've got the complete Mk1 Torque setting chart if you want.
PM your preferred email, then give me a couple of days.)
Easy to get the rocker cover bolts to twist like toffee :shock: if you've had too much porridge. :wink:
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Re: PCV valve

Postby CaptainNorth » Sat Apr 30, 2016 12:23 pm

Thanks OldSpice for the thoughts, yes was reading about the CAS O ring, really need to do the cam belt too but that's in a different league....Thanks for the offer, I've got a Haynes but if that fails I'll drop you a mail - much appreciated - the rocker cover nuts look like metal cheese so I'll go canny!

Cheers
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Re: PCV valve

Postby drumtochty » Sat Apr 30, 2016 1:59 pm

Never tighten any of the 10mm AF nuts and with anything more than a 1/4 socket extension or a 10mm spanner and never more than a quarter turn from reaasonably tight. If you tighten them with any force they will break.
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Re: PCV valve

Postby mgrays » Sun May 01, 2016 12:32 am

Answer to your question is no. The inlet manifold is under vacuum only as this is not a turbocharged engine (normally ;) ) So there is never pressure from the inlet manifold to push oil out of engine crank.

There will be times of resonance when the inlet manifold is under slight pressure but so little as to be irrelevant.

Usually a poorly fitted cam cover (and/or no blobs of sealant in the corners), O ring etc is causing a slow weep.

PCV can be tested by removing and sucking/blowing with your mouth..

If it was turbo'ed (i.e. non standard aftermarket job) then a leaking PCV causes more oil vapour to get into the air filter housing out of the vent at the other side of the cam cover.
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Re: PCV valve

Postby CaptainNorth » Sun May 01, 2016 10:06 am

Thanks Malcolm for the info. I guess I'll change the gaskets and see if the noise persists - it sounds like a waste gate activating when the car is driven hard, and always at approx 4250 RPM but like you say there's no turbo so I guess it cannae be a waste gate. Gaskets en route so I'll change them and take it from there.

Changed the oil and filter, air filter yesterday, diff and gearbox oil and plugs next. Then it just needs a cam belt, a radiator, handbrake adjustment, AC removal or fix and recharge (can't decide), underseal/cavity wax and a Nardi wooden gear knob! And for sure some stuff I haven't identified yet.... :D

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Re: PCV valve

Postby CaptainNorth » Sun May 01, 2016 10:10 am

drumtochty wrote:Never tighten any of the 10mm AF nuts and with anything more than a 1/4 socket extension or a 10mm spanner and never more than a quarter turn from reaasonably tight. If you tighten them with any force they will break.


Cheers Eddie, I hear you
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Re: PCV valve

Postby mgrays » Mon May 02, 2016 4:54 pm

CaptainNorth wrote:, AC removal or fix and recharge (can't decide),


It cost me about £800-1200 I think get AC working again.. new condenser/radiator, new drier, changed pump, second hand pump, used lower pipe, vacuum pump, gas and gauges (locals A/C boys pretty useless last time I tried).

Even when working it is feeble and you only really need it for South of Europe or Dubai in the summer.. (BTDT!!)

I did strip it out for someone here (hence the pump) .. easy job under bonnet, doing it properly and pulling the bits out from the dash is more of a pain.

The Mk1 have an Achilles heel in the piping and there are about 3 types from memory. Mine had the 2 part pipe and it is held by a steel bracket under the radiator; the aluminium rots on contact but it is covered by the steel bracket so you never find the leak until you strip it.. oh and half the times the aluminium nuts cold weld themselves. So easy or cheap it is not..

I would be lubricating the brake calliper pins and under the dust boots of the pistons first.. presume you have done the oil in the gearbox turret already.

The noise.. my guess would be the catalytic convertor heat shield.. that was a fairly standard rattle at one point.
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Re: PCV valve

Postby CaptainNorth » Mon May 02, 2016 9:18 pm

Thanks, I'll post up progress, the noise doesn't sound like a metallic rattle, it's like pressure releasing - a strange one.

Think your experience of the AC probably swings it, sounds a total headache, strip out not a priority but a good job for the winter. I like originality but not that much :-) Going to do the turret when I do the 'box. Also need to do the brake and clutch fluids and check the pads/discs as braking has no bite at all. PO said handbrake adjustment was easy at the back hubs but lasted for just a short time before it slackened off again so need to have a look.

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