Compression Testing - The Results Are In

[robwright]

Oli no offence taken at all mate. I love a good healthy debate and a lot of what you said does make sense. Why should I bother when the car runs perfectly OK. And there in lies the problem it is just OK. A lot of what Simon said is actually true also. I do feel a commitment to the car and if it were about rational thinking then I would have gotten rid of it as soon as the clutch packed up or maybe even sooner after I had my initial Turbo thrill. But no I chose to repair the clutch and carry out a good deal of restoration along the way. The fact I chose to do the clutch myself was not just driven by my sheer tight fistedness but the want to do it myself. I enjoy working on the car as much as I enjoy driving it. Now that I have convinced myself that I will do it I am actually looking forward to the challenge. You must also figure in the practical side as well. Once you start to modify your Turbo you do leave yourself wide open to other issues. Head gaskets etc etc etc. Running a car with high boost requires fuel and if your compresion isn't up to standard then this as in my case leads to very rich mixtures at high boost as some of it is being lost into the crankcase but the ECU doesn't know this and can't compensate. Too much fuel can in turn cause borewash, which itself will only exacerbate the problem. Bit of a catch 22 situation really but one which I have caused so must now remedy [] Simon I too am committed to having working aircon. I have a new compressor, which I wasn't going to fit until I was ready but the old one was making a terrible racket!!! I also have a new receiver drier ready to fit. That will be fitted just prior to the gas going in. All that is required is to get a vacuum pulled on it to test for leaks and then hopefully get some modern r134a gas put into it as you can do if you change all the components. You should ideally change the expansion valve but this is easier said than done on 944s as it is buried behind the dasahboard []

 

[TTM]

Replacing piston rings should actually be doable alone, but it's quite handy to have all the special tools for taking the engine apart as they should avoid a lot of swearing.

While everything is apart I would suggest upgrading to Pauter rods, a DBB turbo from SPS, a 3" exhaust, and and and... []

 

[zcacogp]

Rob,

Good show. Looks like you're committed - in every sense! The only thing I would add is that if a job is worth doing, it's worth doing properly; but I have no doubts you'll do nothing else. All the best and keep us updated. (Photos would be particularly good.)

Chris, I hear what you say, but would add that most (if not all) of those items you list either may cause breakdown, or will deteriorate if not addressed earlier rather than later. And, as such, should be attended to quickly if you intend to either keep the car for any period of time or drive it more than a couple of miles from home. Slightly low compression on an otherwise healthy car fits neither of those two categories, hence my post.


Oli.

 

[Hilux]

ORIGINAL: chrisg

Interesting points Oli, there is a very fine line between 'wasted' money and investment/ prophylaxis for the future. I do know very well exactly where Rob is coming from though.

I had a similar 'feeling' about the fuel/ brake lines on my car and decided to take the plunge last winter - very glad I did. Huge time consuming job, but can now drive it (particularly too and from France/Germany) in the knowledge neither the fuel nor brake lines are corroded.

Bottom line - all of our cars are min 20yrs old and the inevitable rust, corrosion (caliper lift vs iron oxide), degradation of anything rubbr etc has set in. For any 944 of this ilk the following list of recurring jobs/problems seems to crop up:

• Rear fuel or brake lines particularly over the axle
• Head gasket going porous/soggy - more so on Turbo's but also an issue for all 944's
• Caliper plate lift
• Belts (a regular service item though)
• Sills and replacing them
• Turbo & S2 front fog bulbs going - can't remove the light and fails MOT...
• Fuel pump - most noticeable on Turbo's on WOT
• PAS pump and/or lines - usually the cooling loop rottting
• ABS - any of a number of items
• Clutch cylinders giving the pedal on the floor scenario

I'm sure there must be other likely candidates I can't think of too !

Chris

Fuel filters are always forgotten and a pig of a job if (as they invariably are) the fittings are corroded - you dont want to run lean (especially on a Turbo)

I bet there are some near 20 year old filters and associated pipework on tuned gleaming 944`s []

 

[944Turbo]

Rob when you were checking for boost leaks am I correct in thinking you were pressuring from the AFM? this would pressurise the crankcase as the breather enters the J boot - has this process put some doubt in your mind about the piston rings? Still think its best to pressure from the turbo output (input to hard pipe)
Tony

 

[robwright]

ORIGINAL: 944Turbo

Rob when you were checking for boost leaks am I correct in thinking you were pressuring from the AFM? this would pressurise the crankcase as the breather enters the J boot - has this process put some doubt in your mind about the piston rings? Still think its best to pressure from the turbo output (input to hard pipe)
Tony

Yes I was doing it from the AFM mate, which is actually the prescribed method from the manual. I was happy that all the vacuum and boost leaks had been rectified so I moved onto the CT. It was something I have been wanting to do for some time anyway due to the age of the car. It was the lower than normal readings followed the increased wet compression that has led me to suspect the rings are worn.

 

[sulzeruk]

Rob, I have a drop in engine here complete if that would get you round the problem. Also have a very nice forged bottom end with nice unscored bores and a 250 bhp cylinder head than needs a refurb. Easier to do one out of the car and then swap.
Al

 

[George Elliott]

Rob,
This is an interesting thread you have started.
Many points of view and I understand them too having experienced a few 951's, and like yourself - I enjoy working on them.

Chris give a scary list of repairs, I recognise every one...[8|]

The question Why is a good one, if the answer boils down to boredom, curiosity, or a notion in the head (not cylinder head) then Oli is right.
If you don't like the rich mixture, and the smoke, then you are probably right to do the work. I say probably, because if you sell the car immediately, you will not recover the spend - as you know, but then you don't sound like a seller.

I put a Cometic CHG on my 89 car and its not a terrible job. Promax are a good outfit for sensible advice IMExp.

I would not remove the engine, nor skim a perfectly flat head (nor replace the tail-lights whether they have done 80k miles or 180k or 380k, - because they are not broken.[]

I have learned that 951's use Oil largely from the KKK turbo, when I thought it was a bore related thing, maybe you are thinking Valve guides too. I now have a PerfectBore Block and SPS BB Turbo, and Oil top-ups are eliminated. I never believed it was possible. Silkolene / Fuchs 5w 50 Oil & filter every 7k. Opie Oils.

In your shoes, the items I would do are:
Valve Guides (subject to measurement)
Valve lap
Water Pump
Belts and Pulleys
Cometic gasket
Rings
B&S End Bearings
Seals (all)
Gaskets (as required)

Service parts:
Plugs
Dizzy & Rotor
Check Injectors
K&N Air Filter
DV30 check (done as part of boost leak check)
ISV
Replace Fuel Hoses to Rail

Tuning Options:
SPS Turbo
3" DP & Exhaust

Hold the engine on top of the struts and drop the crossmember
drop the sump
build a stack of pallets beside the OSF wheel to stand on
work from above and below

Has to be good for 320bhp and 100k miles following that, and for that power you don't need to spend £1k on rods, beautiful tho they are[8D]

just my 2 penneth.

good luck

George
944t

 

[robwright]

George thanks for your post mate it made for good reading. The turbo on the car is a reman from Lyndsey Racing and has only about 5K on it. Your list apart from the tunning looks exactly like my train of thought. Interseting that you say about supporting the car from above on the strut mounts. Is this is a procedure you have done before or have seen others do? I would definitely be interested in doing this. I am sure that I can manufacture whatever gismo would be necessary to do it. Oh and yes I totally agree about skimming the head. Why skim if it shows no symptoms of blown HG or any other overheating problems.

 

[Mike_Pollock]

Somewhere on YouTube there is a clip of a guy, eastern European I think, with the engine supported on the shock turrets, so he could change the crossmember (I think). He only lifted it about 150mm and as he had a pit the car was level.
The frame looked like an "A" with the top cut off, the angle of the legs apparently matching the angle of the struts.
Not sure if that one would work with the car on ramps, would need a rear brace I would have thought.

 

[JamesO]

Sort of like a strut brace with a ratchet strap hooked around each engine mount maybe?

 

[robwright]

Hmm sounds feasible James. Got me thinking now. Now this is exactly what I like. Solutions to problems. Now isn't this fun. Still I have always contended that you should never re-invent the wheel so any pics from anyone who has done it before would be nice []

 

[944Turbo]

Something along these lines
http://www.machinemart.co.uk/shop/product/details/cec500-enginegearbox-support

 

[robwright]

Tony that is pretty much the same kind of Heath Robinson device I was dreaming up in my own head!! I am sure I can make one for peanuts with things left lying around the workshop. I have come to the decision that I will do the work eventually but only when I have saved up enough to do it. In fact I am crap at saving so I will probably just purchase a little bit each month until I have it all. The list I have so far includes:

Piston rings
Promax widefire HG kit
Big and small end bearings
Crank seal
Balance belt seals
Belts and rollers
Water pump
All the gaskets needed that don't come as part of any kit

I am guessing all that will come to around a grand so it will take me some time to amass all of it. Oh well will give me something to look forward to []

 

[George Elliott]

Rob,
others have answered and Tonys suggestion is spot on
I assisted a reshell many moons ago, but the engine/t-tube/beam/gearbox were treated as one unit, lovely layout.

As the Head is off you won't want the OSF engine mount strapped to the support, but the way the engine is canted over means it should suspend from the NSF engine mount and not obstruct your work area. You can support the torque tube/bell housing from the floor gently with a jack as belt & braces.

You may be aware Lindsay racing do a 3 piece crossmember, perhaps because our American cousins are partial to dropping the pan.[]
I would not agree that the CM is improved by this, nor I suspect would many of us.

I think one of the skills in a project, is keeping to a budget, and ensuring the engine department, suspension dept, brake dept etc remain matched at the end. An open cheque book 951 will quickly run to 996TT money, and good as the 951 is, the Mezger 996 cars are pretty effective straight out of the box.

Good luck with your work.
George

PS Clarks Garage is useful, but you will be aware of that I guess.

 

[colin944]

I completely agree with you Rob on what you are doing.The satiafaction you get from doing your own work can't be bought.When I started my project I would have considered myself to be a fairly competent amature.But during the process I have learnt to weld as well as how to use a metal folder,a grinder,spotweld drill etc.I have also found that printing the relevant parts of the workshop manual and then reading through it a few times before you start has been the best pratice for me.I bought a porsche factory workshop manual on cd and just print the bits I need to do each job.I don't work fast but I am extremely thoroughly to get each part right as I go.
If I was you I would pull the engine out and and do all your work on a stand.If you don't use the car as a daily driver then pull it out and do the engine work over the winter.That way you can do any other wee jobs that you want done at the same time.

 

[robwright]

Thanks for your comments Colin really appreciate them. All of those things you mention I am already skilled in but am not fortunate or rich enough to own them. I do however have a basically (believe it it is in terms of machines) kitted out workshop. But it has all the basic hand tools that I don't have in my garage. All the rest I can figure out [&o]

 

[chrisg]

Rob

A couple of years ago when my car was in at Mark Fish's workshop we had need to get at the rear of the engine without the cross member in the way. We supported it from above using 2 x engine support frames, one a the front of the engine collar/hook just below the water elbow, other at the back off the cam housing.

Obviously you can't do the later if the head is coming off, however, should you need it I have one of the frames/ bar bits of kit from Machine mart which you're more than welcom to use - classically these are used for supporting the engine on transverse mounts for clutch/ gearbox removal.

Let me know if you need to borrow it - happy to drop it in sometime as I spend most of my business life driving up and down the A1 to and from Doncaster/Scunthorpe etc.

Chris

 

[barks944]

ORIGINAL: chrisg

We supported it from above using 2 x engine support frames, one a the front of the engine collar/hook just below the water elbow, other at the back off the cam housing.

Obviously you can't do the later if the head is coming off, however, should you need it I have one of the frames/ bar bits of kit from Machine mart which you're more than welcom to use - classically these are used for supporting the engine on transverse mounts for clutch/ gearbox removal.

I have done it using a strong bar across the front strut towers and use the engine mount brackets and some good straps or rope. Can also use a chain with the head studs and a bolt as a backup.

Edit: If you take the oil pump off for any reason make sure you put it back sealing the face against the block using Locktite 574. I wouldn't suggest using anything else unless you know it will work. Don't ask how I know...

 

[robwright]

ORIGINAL: chrisg

Rob

A couple of years ago when my car was in at Mark Fish's workshop we had need to get at the rear of the engine without the cross member in the way. We supported it from above using 2 x engine support frames, one a the  front of the engine collar/hook just below the water elbow, other at the back off the cam housing.

Obviously you can't do the later if the head is coming off, however, should you need it I have one of the frames/ bar bits of kit from Machine mart which you're more than welcom to use - classically these are used for supporting the engine on transverse mounts for clutch/ gearbox removal.

Let me know if you need to borrow it - happy to drop it in sometime as I spend most of my business life driving up and down the A1 to and from Doncaster/Scunthorpe etc.

Chris

Chris that is a very kind offer and I am sure that I will take you up on that. One of the things that I love about this forum. I will be in touch when I get round to doing the work. It may be some time in the future though. Thanks again.