Joining the 996 engine rebuild club

[m444ttb]

Well this was a post i hoped not to make. I bought my 89k mile 2002 Carrera 4 from a local garage back in late November. I'd noticied it I didn't use the car for over two weeks it would puff some blue smoke on start up. Autofarm checked the bores and they were scoring free and more frequent usage never saw it really return.

The car has always had a little oil usage but since I've had an oil change done the rate seems to have gone up. Based on Autofarm's findings at the time (condition of the used oil) I suspect it had some thicker and quite old stuff in it. I popped out the other evening to enjoy some country lates with another Pork owning PHer and this saw it use a noticeable quantity of oil. All in over 450 miles since Autofarm serviced it to when i dropped it off for some other bits to be sorted it used the full range on the dip stick, which i think is 1.5L. Clearly things aren't good. Autofarm have confirmed that it has some leaky piston rings, particularly on cyclinder 5 (on the right bank i think) and th e(new) plugs were quite black and the new tailpipe I have on the right side (exit for left bank - the less leaky side!) was blackening nicely after my evening joy ride.

I'm not sure quite where i'm going with this post so you'll forgive the rambling. I love driving the car, although i was considering selling, but think i'm going to have to suck it up and get a loan to pay for a proper rebuild that will take care of all the 'usual' 996 issues plus some service items such as clutch and water pump. Then keep the thing a long time to justify it.

I'm telling myself that in 12 months time when it's all paid for I'll be able to sleep easy not worring about the engine going bang at any moment but I can't get the thought of spending more than half the current value of the car on the engine out of my head. Not to mention all the other things I could spend that sort of cash on

Edited by m444ttb on Wednesday 15th July 14:39

[m444ttb]

I'll either have Autofarm do the work as they maintain the car so makes some sense or I'll go to Hartech. Before i bought it i had a chat with Hartech and priced up their ultimate rebuild at £8k +VAT.

rubystone said:

What thickness oil was used for the oil change? Presumably NOT 0 rated...

The oil change i had done at Autofarm? I can't entirely remember but i think they use 10w-40? I'll check when i pick it up Saturday. As for what came out of it I've honestly no idea. Autofarm thought that from the state of the drain plug it may have skipped a service as they struggled to get it out. Prior to that it had been at Swindon and Reading OPCs though.

It's annoying that the car is otherwise really good. Or perhaps that's a good thing?

[m444ttb]

rubystone said:

Are you sure it needs a rebuild? Maybe just top-end if it's guides?

I'll talk to Autofarm on Saturday and see what they think. What i dont want to do is throw a few grand at it and still have that nagging doubt about the IMS, bore score, etc. It's a tough choice but at least i like the car a lot.

[m444ttb]

I don't think I could punt it on for a big loss. I'd rather chuck more cash at it and at least feel like I had something to show. I'd be less pissed off if this was the first time something like this had happened to me. My lovely 80k mile BMW M52 nikasil engine with it's oval cylinders was fun back in 2005!

[m444ttb]

It was only for 6 months and having tried to claim for something else a waste of paper anyway. Given this is piston rings I suspect they would have declined it as wear and tear.

Edited by m444ttb on Wednesday 15th July 21:19

[m444ttb]

Back in those days I'd imagine British people considered reliable to mean didn't crumble to dust within 12 months and would start most winter mornings!

[m444ttb]

IknowJoseph said:

Might be worth asking if they suggest the new short block engine - I've had a quick chat with Steve about it down there in the past.

Surely a Porsche owner i need to obsess over matching numbers?

[m444ttb]

Off to Autofarm to collect the car in a minute. I've asked them to prepare me prices on a range of options from minimal fix up to do everything including taking it out to 3.9L. Anyone fancy a guess at the spread of prices?

[m444ttb]

Unfortunately Steve @ Autofarm had left and not given anyone else the prices so will have to wait until I can speak to him on Monday. My guess is £5k-£15k with the top end including 3.9L conversion with cams and re-map (c.390bhp apparently).

Anyhow what I do have are the results from the investigation work they did. All six bores look fine. The leakage test showed the following:

Cyl 1 10%
Cyl 2 10%
Cyl 3 8%
Cyl 4 9%
Cyl 5 13%
Cyl 6 8%

And the compression test the following:
Cyl 1 260psi
Cyl 2 270psi
Cyl 3 260psi
Cyl 4 260psi
Cyl 5 270psi
Cyl 6 270psi

I'm unsure what normal values are for an M96 or indeed any other engine but in told they've seen much worse than 13% leakage plenty of times.

Edited by m444ttb on Saturday 18th July 16:16

[m444ttb]

Trev450 said:

If the bores are fine I presume you are going for the 3.9 conversion purely for the extra performance it will give.

I'm probably not going for it, but if I end up doing something with the bores then it will be a consideration. The trouble is I'm reticent about spending a big wedge of cash (which it is regardless of what I do) and leaving some big worry like bore scoring there. I'd do the IMS shaft and bearing, chains, water pump, etc regardless though.

[m444ttb]

It's hard to know who or what to believe on the liner front. However what Hartech say makes sense to me. Same material therefore same thermal expansion rate. How much of a problem is it though is the question. I wouldn't want to choose a liner solution where there's a chance or it becoming a new issue. Are all steel liners (like Autofarm's) created equal?

[m444ttb]

Interesting reading as always. Thanks Baz.

I'm still not sure what I'm doing. Someone at Hartech was kind enough to give me a run down of an 'ultimate rebuild' package before i bought the car so I know what that will cost and what it will cover. I may leave it a few months as things stand. If i'm considering a full rebuild there isn't much more that can go wrong in the next couple of months.

[m444ttb]

I thougthI'd up as the car has been at Hartech a couple of weeks and the engine has now been removed, stripped down and inspected.

In terms of oil usage there were no single big issues. The air-oil seperator wasn't great, there were a few leaks, valve guides worn and valve guide seals very hard. However no more scoring etc than would be expected for c.91k miles.

The more important findings, which are pleasing in terms of justifying the whole spend but otherwise quite alarming are that the IMS bearing was about to let go (by the sounds of it at any moment) and the crank bearings were just down to the copper. A very expensive job could have become very VERY expensive if the whole lot had grenaded and I'd needed a second hand engine on top.

So i'm sticking to the plan i had, which is Hartech's full works rebuild jsut for peace of mind. So 6x new bores & re-coated pistons, new 997 IMS shaft and bearing, timing chain set, etc etc etc. I'll also replace the AOS, clutch, water pump, valve guides & seals, a cam sensor, oil cooler, rubber proposhaft joints, both PSE valves, exhaust clamps and the brake pipes under the back end. The price is, of course, fairly eye watering and more so as a percentage of the car's value but I love it and want to keep it. Hopefully back with me pre-Christmas for running in.

[m444ttb]

It needed some sort rebuild regardless. I'm jsut going to extra mile as bar as potential bore scoring goes.

[m444ttb]

My car is, subject to an MoT, all ready for collection. Unfortunately i can't make it up to Bolton until 9th January Grant @ Hartech thinks the car drives really well too. I wonder whether suspension work has taken place at some point. There's no receipt from a Porsche OPC (or other garage) for it amongst my folder of 'stuff' though. The engine will require a little running in, but pretty much involves me not driving it really hard but making sure i do use some revs. A further oil change in a couple of thousand miles onto the good stuff from Millers will then be required and I'm away. Just need to pay for it now.