Roygarth

My smoking problem has been diagnosed as worn valve guides. Bloody annoying as car has on 50K miles and I only discovered it when I took cat off (should have left it on!)

Well respected Norfolk specialist has quoted £1300.

JZ Machtec quote £2600 for 'top end overhaul' Is this basically a valve guide fix and the price difference due to JZ being near London, or does top end overhaul involve more than fixing worn valve guides?

Thanks in advance!

Piers

George Stevens

Piers

I had the same problem on my 1977 Carrera 3.0.

It is difficult to get a fixed price for a top end rebuild because once the engine is out of the car and the heads are off you are committed.

A good vigilant specialist will also do a pressure test, check piston ring wear and check all gaskets, check the clutch and flywheel etc, etc etc.

So what did I do with my Carrera 3.0 when they were quoting anything from £1500 plus VAT to £5000?........

.....I just kept topping up the oil on a regular basis and lived with it!!!

johnfm

I think there was an extensive posting some time ago by a guy , Mario Costa-Sa I think, who had a re-build at JZM. Loads of pictures etc, even the bill - parts & labour - got posted. Try ringing the guys at JZM. I live up North & can never use them, but I've spoken to Jonas, who is always VERY helpful.

911-TOUR

Roygarth,

Don't get taken on this. I'm not sure what valve guide replacement entails on a 964, but I'm pretty sure that you *don't* need a top-end overhaul at 50K. A skilled mechanic should be able to replace the worn valve guides by simply removing the heat exchangers and valve covers. There's no reason to pull the cylinder heads as well. (At least I can't think of a good one)

sean

Christer

Piers

I think you will find that the difference in price quoted ties in with what Sean is saying. You can pay £1300 to get the valve guides replaced. HOPEFULLY this will fix your problems. Or you can pay £2600 for the basic engine rebuild while you are 'in there'. This will not only sort your current problems out, but will take a look at the complete engine - you never know what is around the corner.

Mileage is not the only factor in determining the condition of an engine. Age and usage comes into play as well. In the survey on John Miles site regarding engine rebuilds last year, there were a few 964 owners who reported that theirs had been done at 50k miles or earlier.

Basically IMHO, it comes down to money. If you don't want to spend any more than necessary, then I would shop around and get the best quote for the particualr work you need done, bearing in mind that I guess there will be a slight risk that the diagnosis could be - shall we say 'incomplete'. If you don't mind spending the money, then of course it does make sense to go for the engine rebuild as you will sort the current problem out but also know what else is going on in there. It would be gutting to find out that something else needs doing later in the year when you have spent £1300 sorting a particular problem out. Even if you have the rebuild done and there doesn't seem to be a lot wrong in there - you still have an engine then that should last you many years with no or minimal oil leaks and all that other stuff.

Just my 0.5 ĝre.

Roygarth

Thanks guys. I'll wait until end of summer and make a decision:
1) Live with it a la George's approach - but embarassing when ball of smoke envelopes car on Kings Road!
2) Put cat back on and sell it - only kidding, I do have a concience.
3) Relay your input to Norfolk man and ask him to give it a full once over whilst he's 'in there'.

Thanks again.
Piers

Christer

Piers

What's with Norfolk? Do you live up there and travel down to 'cruise' the King's Road?

Bill Gregory

I don't know how you can replace the valve guides without pulling the heads off. If the heads are coming off, and you track your 964, I would recommend they replace the connecting rod bottom bolts with Raceware or ARP or similar bolts. On the 3.2L and later engines, Porsche downsized the bolts to 9mm (from 10mm). If the engine is reved high, as they are at the track, and then overreved, the 9mm bolts can let go - not a pretty fix after the fact. Not expensive to do with the engine dropped and the heads already off.

With the engine dropped, you might consider replacing the various seals - timing chain covers, power steering pump, etc. I have 50K on mine, and will need to redo seals in the near future.

As mentioned, dropped engine is a good time to inspect the clutch and flywheel.

A Quiet Boom

I have to agree with Bill on this one, if you have the money upgrade and replace what you can while the motor's apart. Besides that worn valve guides can lead to other more serious problems, like damaged valves etc. It's the old saying, "pay a little now or a lot later"

Roygarth

[quote]Originally posted by Christer:
<strong>Piers

What's with Norfolk? Do you live up there and travel down to 'cruise' the King's Road? </strong><hr></blockquote>

Yes, I live there at weekends! I keep 964 there most of time - the roads up there are amazing!

Jeff Curtis

Roygarth, I wouldn't think you have valve guide issues. I just removed my catalytic converter a few months ago and installed a "Euro-Premuffler"...now my car puffs smoke at stop lights, just as you describe.

My car runs great, with minimal oil consumption...it just LEAKS it out! :S

You can alleviate the smoke condition by either putting your catalytic back on or having a chip tuned to your upgrades. I thought maybe I had goofed up the O2 sensor while changing everything out...but I've been told that's doubtful, although possible.

I get embarrassed at stoplights from time to time as the issue is sporatic. About the time I pull up to a car with a cutie in it, I see the smoke screen blow up in her face...embarrassing as hell! <img src="graemlins/cussing.gif" border="0" alt="[grrrrrrr]" />

I have a habit of taking care of small issues such as this one slowly but surely...usually dependent upon interest level, time of day, etc.

To clear up a few issues. For a valve job, the engine does have to be removed from the vehicle, heads OFF - no other way to do it.

Also, it's quite a bit more work to remove the cylinders/pistons to plug in new rod bolts...then it's doubtful you'll get a good torque reading as the Racewear rodbolts suggest measuring rod bolt "stretch" until a certain length is achieved, when compared to original length before torquing.

As you may be able to tell...you'd have to have some type of fancy measuring device to do just that! Their other suggestion is 65-75lbs, if I remember correctly...as I had installed them on my 3.0L - BUT had the engine completely disassembled...so I measured stretch.

Either way, I wouldn't imagine a shop would let you off cheap for that sidebar.