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Fixing my 911's engine - Take 2

VinceB

Hockenheim
Joined
26 Feb 2012
Messages
632
Hi All,

I posted this on another motors related forum and to be honest I forgot about this place until today so thought I would come on and post:

It's been a while since I've posted any threads on motors, I think the last one was where my engine was out getting what I thought would be sorted once and for all. But alas it was not to be, I got the car back and within weeks of spending £2900 on repairs the old problem reared its head again and I had oil mixing with my water. But this was not all, since the last big bill I now had a rip in my roof and serious problems with the wheels/suspension which was causing big problems with the way the car gets down the road.

For those of you that don't know the car here is a picture of what it looks like

imag0475h.jpg


I parked the car up in my garage and left it for 4 or 5 months while deciding what to do, but was always keeping my ears open for an opportunity to find workshop space and or somebody who was willing to help me get this thing fixed. I was not ready to give up on the old girl just yet.

A few weeks ago such an opportunity came up, the story is a long one so I won't go into it but the outcome was somebody that I can trust was willing to give up space and his time so that work could commence on my poorly old 911. Now I should point out that not all the work is being done by me but I have been inspecting the car and helping where I can around my own work schedule.

Having read the autofarm pdf about my engine: http://www.autofarm.co.uk/pdf/Total911_July06.pdf and being well aware of the issues I have, I am still convinced that my cylinder head on the left hand side is the cause of the cars problems so that was the first thing that I wanted tested but It means a massive commitment in stripping the engine block right down to the bottom end.

First of all we got the car up on the ramp and removed the bumper and the manifolds, normally on an old Porsche this job would be a royal pain in the arse because the manifold bolts are notorious for rusting away, but on my car this was easy as I had them drilled out and refitted with captive nut alloy replacements last time the engine was out. Good start... until you look up the manifold on the left hand side and see signs of water inside the cylinder head which is not so good and difficult to get pictures of. So I didn't but here are a couple of the car up on the ramp.

b75l.jpg

qrki.jpg


Next up was getting the engine on a bench and stripping it down exposing all of the tasty bits while getting both heads sent to a specialist to be looked at, pressure tested for cracks, skimmed if they were good and sent back. So that's what happened and my heads should be back with me on Monday. The bad news is that my suspicions have been confirmed and the old left hand head is toast, it's got a terminal crack that runs from a bolted face where it meets the hydraulic tappets across to a core plug, I'll get some pics of this when I get it back.

Meanwhile I have been busy locating a new head and yesterday I struck gold and found a head in Yorkshire that is apparently in good shape with no cracks and will be shipped to me in the week, it comes from a car of the same age and roughly the same mileage as my car. Speaking to the guy he tells me it was from his old engine which had problems with the bottom end, he assures me that the head is in good shape, but the only down side is that it has a manifold attached to it as the bolts are corroded. So I decide to go for it and will removed the manifold and then get the head sent to be checked for cracks and be skimmed before it goes on the car. £500 for the part seemed a reasonable price as well, if it really is in as good shape as the guy claims.

The next thing to do while the engine is in pieces on the bench is to inspect some of the other parts of this engine to get an idea of what I'm in for in rebuild costs so let's start with a few pictures of what we are looking at.

Here is the block on a bench with the heads removed looking at it from the front.

w81g.jpg


All the pulleys are in great shape no groaning bearings, new oil cooler waiting to be fitted at the top right under the blue towel, this was replaced just a few months back but I'm putting another new one on this anyway.

My biggest fear was looking at the bores and seeing scores or worse cracks. But when you get up close and take a look they are in really great shape, no scores at all and no cracking, pistons also look in great shape. This is the left hand side where we have cylinder head issues:

dzdy.jpg


While we are on the main block let's take a look around the back of the block where the RMS (rear main seal) and IMS (Intermediate shaft)are located, these are the weak points in the block so it's good to at least inspect them and decide what to do while the engine is in pieces.

First up the RMS which is normally hidden behind the dual mass flywheel, more on this later:

ox70.jpg



The RMS looks in good enough nick but is weeping a little so we are going to replace it while the engine is in pieces.

Next up down the bottom of the block we have the IMS:

jgeq.jpg


Looks pretty nasty down there, so we take it off with a 10mi and a screwdriver then remove the flange cover to expose the ims bearing:

dy7o.jpg


Now if you know your Porsches you know that this little ***** is the bane of any 996 or 986 owners life and I'm sure it has been the cause of many sleepless nights, if it gives way the bottom end of these engines is normally toast. Now if there are issues you can feel play in the bearing while it is in situ, my one however is rock solid with no discernible play, nether the less I decided to see what is out there and have found a company that sell an uprated bearing called an LN engineering ceramic ball bearing. The company is called revolution Porsche and I had a lengthy conversation with a guy from there tonight about the bearing and am deciding what I want to do with it. The LN unit is £400 +vat and requires a special tool to fit. Or as my unit looks in good shape do I just leave it?... Decisions... I'm not sure just yet but will decide in the week.

Next up its time to inspect the cams and variocam system, again the cams are showing little wear and the cam lobes are still in great condition. All of the sprockets also look good with no signs of cracks or damage.

a96s.jpg


Next up clutch and dual mass flywheel:

ptum.jpg


The flywheel is in great shape but the underside of the clutch is basically on metal so a new clutch is needed when it goes back together:

yjfv.jpg


The release bearing is also shot so will need replacing its grinding away up there.

So what are we left with, well this is a box of the good bits the rockers are fine, and will need new gaskets, the head bolts will need replacing, I almost fell off my chair when I was told the bolts are the best part of £10 each, seems reasonable until you realise you need 24 of them.

jah5.jpg


Right now that is where I am at with the car, I am sure I will tally up total costs at the end but so far in parts alone I have spent a small fortune but at least this time when it goes back together I will have personally looked at every part of the engine and know exactly what condition it is in.
 
Thanks for this.Youve gone to a lot of effort, to educate the less knowledgeable of us.
its a very interesting thread,I shall follow closely.


I think thats the 3rd IMS bearing in s few days, thats been exposed or replaced on this forum that has been fine.
Perhaps not the kiss of death we have all been led to believe?Id still replace though,if nothing else it will help with resale.
 
I am considering it, just don't know what part to go for, somebody is telling me that getting a pelecan parts oem unit is a good idea. I'm not so sure so am still weighing up my options. Mine does look in good shape so i honestly might think about doing this next time.
 
VinceB said:
I am considering it, just don't know what part to go for, somebody is telling me that getting a pelecan parts oem unit is a good idea. I'm not so sure so am still weighing up my options. Mine does look in good shape so i honestly might think about doing this next time.
Im pretty sure that Autostrausse use the LN bearing.That would be good enough recommendation for me. :thumbs: :thumbs:
 
Do you think you missed the cracked head last time you had the engine apart, expensive mistake if so? Good effort with getting to grips with it yourself, there are a few pitfalls with these engines that you need to be careful with before putting it all back together again. Check, check and check again and take lots of pics for reference (and also for us on here).

Ask Baz/Grant at Hartech about the IMS bearing, it makes sense to change it whilst you are there, if you have your engine apart as much as you do, it doesn't take too much more effort to split the crankcase and get the IMS out and sent to them for a bearing fitted for a lot less than the LN type. It will require a special tool to fit the 3 pistons back to the con rods once assembling the crankcases again, I have a tool for that if you decide to.
You will also get to see the condition of your bottom end and chain guides so no other nasty surprises are waiting for you down the line.

I also have a OPC bought clutch release bearing that's only covered 900 miles if you require one for a third of OPC prices.
 
infrasilver said:
Do you think you missed the cracked head last time you had the engine apart, expensive mistake if so? Good effort with getting to grips with it yourself, there are a few pitfalls with these engines that you need to be careful with before putting it all back together again. Check, check and check again and take lots of pics for reference (and also for us on here).

Ask Baz/Grant at Hartech about the IMS bearing, it makes sense to change it whilst you are there, if you have your engine apart as much as you do, it doesn't take too much more effort to split the crankcase and get the IMS out and sent to them for a bearing fitted for a lot less than the LN type. It will require a special tool to fit the 3 pistons back to the con rods once assembling the crankcases again, I have a tool for that if you decide to.
You will also get to see the condition of your bottom end and chain guides so no other nasty surprises are waiting for you down the line.

I also have a OPC bought clutch release bearing that's only covered 900 miles if you require one for a third of OPC prices.

Yes the cracked head was missed last time the engine was out around 6 months ago. But that time I had little to do with the rebuild and left it somewhere to be investigated. It was returned a few months later but still not right.

This time I parked it up because I wanted an opportunity to get to grips with it a bit more myself, when that came up I jumped at the chance. So yea I guess an expensive mistake.

The clutch release bearing is that the same on the 3.6 as the 3.4?

I'm still really not sure what if anything I want to do on the bottom end.
 
VinceB said:
infrasilver said:
Do you think you missed the cracked head last time you had the engine apart, expensive mistake if so? Good effort with getting to grips with it yourself, there are a few pitfalls with these engines that you need to be careful with before putting it all back together again. Check, check and check again and take lots of pics for reference (and also for us on here).

Ask Baz/Grant at Hartech about the IMS bearing, it makes sense to change it whilst you are there, if you have your engine apart as much as you do, it doesn't take too much more effort to split the crankcase and get the IMS out and sent to them for a bearing fitted for a lot less than the LN type. It will require a special tool to fit the 3 pistons back to the con rods once assembling the crankcases again, I have a tool for that if you decide to.
You will also get to see the condition of your bottom end and chain guides so no other nasty surprises are waiting for you down the line.

I also have a OPC bought clutch release bearing that's only covered 900 miles if you require one for a third of OPC prices.

Yes the cracked head was missed last time the engine was out around 6 months ago. But that time I had little to do with the rebuild and left it somewhere to be investigated. It was returned a few months later but still not right.

This time I parked it up because I wanted an opportunity to get to grips with it a bit more myself, when that came up I jumped at the chance. So yea I guess an expensive mistake.

The clutch release bearing is that the same on the 3.6 as the 3.4?

I'm still really not sure what if anything I want to do on the bottom end.

One reason I did my own rebuild was not trusting mechanics on my car and I wanted to learn more about the car. If you need any info (as you probably already know) just ask on this forum its got a wealth of knowledge and can guide you through most steps of the process.

I think the 3.4 and 3.6 use the same release bearing but worth double checking.
 
infrasilver said:
VinceB said:
infrasilver said:
Do you think you missed the cracked head last time you had the engine apart, expensive mistake if so? Good effort with getting to grips with it yourself, there are a few pitfalls with these engines that you need to be careful with before putting it all back together again. Check, check and check again and take lots of pics for reference (and also for us on here).

Ask Baz/Grant at Hartech about the IMS bearing, it makes sense to change it whilst you are there, if you have your engine apart as much as you do, it doesn't take too much more effort to split the crankcase and get the IMS out and sent to them for a bearing fitted for a lot less than the LN type. It will require a special tool to fit the 3 pistons back to the con rods once assembling the crankcases again, I have a tool for that if you decide to.
You will also get to see the condition of your bottom end and chain guides so no other nasty surprises are waiting for you down the line.

I also have a OPC bought clutch release bearing that's only covered 900 miles if you require one for a third of OPC prices.

Yes the cracked head was missed last time the engine was out around 6 months ago. But that time I had little to do with the rebuild and left it somewhere to be investigated. It was returned a few months later but still not right.

This time I parked it up because I wanted an opportunity to get to grips with it a bit more myself, when that came up I jumped at the chance. So yea I guess an expensive mistake.

The clutch release bearing is that the same on the 3.6 as the 3.4?

I'm still really not sure what if anything I want to do on the bottom end.

One reason I did my own rebuild was not trusting mechanics on my car and I wanted to learn more about the car. If you need any info (as you probably already know) just ask on this forum its got a wealth of knowledge and can guide you through most steps of the process.

I think the 3.4 and 3.6 use the same release bearing but worth double checking.

Thanks for that I will check and let you know. What's the cost of one from opc?
 
Good News :thumbs: The company I sent my heads to rang me today and they have found me a new head £275 +vat. It's all tested, skimmed and ready to go in. Should be here tomorrow. Now all I need to do is work out if I am going to replace the IMS bearing or not. :D

Oh yea, I also need to need to call the other guy up in yorkshire and tell him I have found one
 
One option to consider with the engine out is to address the cause of oval bores and scoring. I'd suggest you might like to speak to Grant or Baz at Hartech and sound out their advice and suggestions. I know on eof the factors is overheating and to that end, when they rebuild, they install a low tem thermostat but more importantly they machine the water channels to improve water flow to offset the risk of overheating - particularly cylinder 5 and 6 on bank 2. I just think that with the lions share of labour covered by you, their advice might be adding value to what else to consider.
 
So I haven't updated this thread in a while as I declared the car sorn when it come back from the heads being rebuilt, things basically took a turn for the worst after a few miles as the car sprung a leak from the oil cooler. The mechanic also done something stupid and landed himself in prison and getting the car back became a bit of a faf.

Because I was in the process of buying a new house I didn't have the money to finish everything I wanted to do and decided to park it up for another day. Well that day came last week and having moved into the new place and done some of refurbishments that were required it was time to get started.

So where is the car at? The engine is back together and back in the car and so far the following work has been done.

RMS, 1 New cylinder head, both heads checked for leaks and rebuilt. New oil cooler.

But the cooling system is still the old one and wasn't flushed very well at all. So we still have the intermix. This time though I have a garage with power and time to mess about with the car as much as I like so decided to start stripping her down and fixing everything else that needed doing.

First order of service was getting the front end off and the radiators off of the car:






More of the same... more disassembling trying to get the entire cooling system removed.


Yum Tasty intermix.



Pipes cleaned and rads flushed, currently taking over my office but this is fine still haven't decorated it, new rads will be going on but for testing purposes these will be going back on the car for a few more flushes.




The front end looking sorry for itself.



Starting to strip down some of the rear of the car, spoiler off, air box off.




Throttle Body Removed, still need to get the intake off.



My little pile of parts.

Still a shed load to do and I have more photos as I have now removed the intake and have a clear view of the oil cooler. When I was there I noticed that there is a fair amount of oil residue in the intake. Does anybody know the cause of this I am guessing air oil separator?



Right hand intake removed, we now have a clear shot at the oil cooler.



Filthy intakes.





And that's about where we are up to so far. Plenty of parts off of the car, even more to come off. While its sorn I am going to do everything that it needs so that means brakes, caliper refurb, all new cooling system might be a must, might even put in a middle rad. Not sure yet, for now I am happy with the progress over the last few days :)
 
Great thread, thanks for sharing. The pics are awesome ! I wish I had such talent and patience.
 
What with reading all these posts the last few days about the look of the turbo and replacing some parts with gt3 parts It got me thinking, and bear with me here as i'm not even sure.

I've got some damage to the bumper and was thinking a respray or possibly a new bumper as there is some webbing under the paint that came back through after its last respray.

This time there is also a nice scuff to contend with I have no idea how it got there but I have to deal with it:

IMAG0600.jpg


Anyway my car has aero skirts so should I also think about the gt3 mk1 bumper and rear diffusers or is this too much for a c4 cab?
 

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