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Top End Rebuild


ByronBayChris

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My car went for an annual oil change and general checkup prior to heading north.

Apart from new rear rotors, it needs a top end rebuild

It is with the lovely bunch at Jocaro, and I have been driving the rather butch Toyota Yaris (my daughter laughed LOUDLY when I drove in).

Is $8-$10 reasonable, and what else should I do once I am in there? Keep in mind it is a tip, and of rather ordinary body condition also.....more of a neglected animal when I rescued it.

Comments and thoughts please gents (and ladies).

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I'm hoping you mean 8-10k not $10 LOL!

 

My body shape on my 952 isn't perfect, but the running gear is superb. I rebuilt mine last year, but it was a full rebuild, piston rings, bearings ect. But with a rebuilt top end, you should notice a difference.

the "while your in there" are the 4 most dangerous words i know of.  

This is what happened to me:

for my top end.. I had a stock head that the ports where polished and port matched with the intake. That's it. When i did the rebuild.. well i ended up with a custom head (ported, polished, larger intake valves, custom valve springs & titanium retainers) and to compliment the custom head, i got a custom camshaft which is quite wild. 

 

I would say, leave it.. and just replace what needs replacing such as seals ect. If you need to replace valve springs, then yeah, get upgraded ones with titanium retainers.. If you've got some money to spend on it, a mild port and polish may make a little difference. 

 

But when you start increasing the engines VE(volumetric efficiency), other parts become bottle necks. Intake/airfilter > Throttle body > intake manifold > head intake (valves & ports) > Exhaust ports (which is quite rare) > Exhaust manifold > Exhaust

 

Change one and the rest should be looked at to gain the maximum output for your money spent. 

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Bummer!

Chris. How many kms on the car?

Did they do a leak down test or perform the "wiggle" test on the valves? If so, what were the results?

Are you burning oil?

Seems that there is the school of thought that the 993s require a top end at around 150Ks.

The factory valve guides are known to be made of cheese!

I would imagine a set of rings wouldn't go astray.

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Chris

Be careful.

Get a second opinion before you jump.

There have been too many 993 owners drawn into the bottomless pit of a top end rebuild, when a damn good thrashing would have been the cheaper option.

Tiptronic gives everything an easier time than a manual but it also means you're not revving the whatnots out of it as often, and that's something that a 911 doesn't mind, and which clears the carbon.

There's a fair bit of chatter about exactly this issue on the net, and it would be worth reading up, and then finding another person to diagnose the condition.

Good luck with it.

Regards

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+1

Good advice from Simon, considering it is a Tip also.

Even a 911 needs the odd "Italian tune up"!

Although Jocaro is a respected shop, second opinion would be wise before handing over 10 large!

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Bummer!

Chris. How many kms on the car?

Did they do a leak down test or perform the "wiggle" test on the valves? If so, what were the results?

Are you burning oil?

Seems that there is the school of thought that the 993s require a top end at around 150Ks.

The factory valve guides are known to be made of cheese!

I would imagine a set of rings wouldn't go astray.

Odometer shows 130k, how Kelvin thinks maybe more.

They do a leak down test and it got quite poor results.

It also drops oil onto the heater pipes, and Louie had also indicated that it might need a rebuild if he could not cure the smell.

I will get the number

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Chris

Be careful.

Get a second opinion before you jump.

There have been too many 993 owners drawn into the bottomless pit of a top end rebuild, when a damn good thrashing would have been the cheaper option.

Tiptronic gives everything an easier time than a manual but it also means you're not revving the whatnots out of it as often, and that's something that a 911 doesn't mind, and which clears the carbon.

There's a fair bit of chatter about exactly this issue on the net, and it would be worth reading up, and then finding another person to diagnose the condition.

Good luck with it.

Regards

Thanks simon

Doing some more digging now

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Compression test results between 90 and 130. Apparently should be around 200.

Also oil leaks, so he assures me that a good thrashing will not help too much.

I usually drive in manual anyway and it gets a constant gear change revs of 4 where possible

Is that compression bad or really bad?

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compression is low but then again i'm no mechanic...look on the bright side, $10k on a 993 and you have peace of mind that the top end is done i think in the long run is a good investement...especially if you ever want to move it on (but why would you, 993's are absolute horn!)

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Compression test results between 90 and 130. Apparently should be around 200.

Also oil leaks, so he assures me that a good thrashing will not help too much.

I usually drive in manual anyway and it gets a constant gear change revs of 4 where possible

Is that compression bad or really bad?

 

is it one cylinder that's 90 and the rest are around 130? or is it across the range?

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Comp is certainly low. I have the same sort of Kms on mine and trust me, it sees the dark side of 4000rpm regularly, as these cars should.

There is no doubt that you should regularly take your 993 on a "spirited" drive to keep things in check as far as excessive carbon build up is concerned. 

 

Changing gears at 4000rpm at the high end will eventually see you back at the shop. These engines are designed to cop a regular thrashing and don't be afraid to push close to the redline on the odd occasion.

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Your compression is way to low. to put that in perspective.. My compression is 125 125 125 125 (should be 140 but the camshaft brings it down) across all 4 cylinders. Now mine is an 8v 4 cylinder turbo. 8:1 CR

 

The imbalance also isn't right. Just so you know that if you rebuild the top end, your compression may indeed raise but it may not be factory specs. If there's an imbalance still.. Then your piston rings are the culprit. 

 

Who ever did the compression test, i hope they did it with the throttle open and car warmed up. makes a huge difference. 

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dont know what sort of variations there are as far as compression tests.. but i think i recall mine being around 180-185 across all.. i could be wrong on that number, but think that was it

 

I thought leak down tests are more accurate and a better gauge for engine health

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