FlyingDutchman

my 89 C4 engine (89k miles) is out of the car on an engine stand. I have removed most of the parts on top of the engine (engine shroud, fan/alternator, intakes etc).I am not planning to take the heads off, my goal is to make it (mostly) leak free.
I'm planning to replace any gaskets/seals that i have access to. I thinking about the valve covers seals, timing chain cover seals, breather gasket, front & rear main seals. Further more I am going to replace the plugs and wires. The engine wiring hardness is quite hard where it sits inside the engine shroud, I hope that is ok. What else should I replace? Sensors??

thanks,
Arthur

Rocket Rob

Check your cooling fan bearing. Does the fan wobble? The other thing to consider, is have you replaced your fuel lines? They are now 30+ years old. Same with your breather hoses. All of the rubber is now aging out. You could also replace the fuel injector seals and possibly have the injectors cleaned and tested.

r-mm

If you're going to reassemble it on the stand I would smoke test it before you do to catch any issues.

I'd replace the cylinder head temp sensor (note the part is superseded and you need to crimp a weatherpack type terminal on to adapt it to the 964 harness). I'd likely replace the crank position sensor as well, and gap it accurately, add a drop of loctite to the bolts that hold it inplace.

Most would replace the clutch pivots as well.

Re fuel injectors: I had a major issue getting them cleaned then letting them sit for a month or so before firing the engine. In that time they seized, perhaps the cleaning fluid made them bind. Whether this was the fault of the cleaning service or not I don't know (they remedied it) but keep it in mind based on your schedule. Most cleaning services also replace the o-rings. One thing none of them tell you is they strip the paint from the body of the injector and if you don't repaint them, they rust.

FlyingDutchman

I did a leakdown test on the engine, severe leakage (like 80%) from the exhaust port on cylinder #1. Pulled the heads/cam towers and the cylinders and pistons. Now I'm trying to remove the rocker shafts, I got the bolts out but the cone washers (I believe that's what they are called) are stuck, any tips how to get them out?

CraigT

There are alen heads on each side. When tighened the ends of the shaft expand to hold them in place. Loosen them and they should slide out.
No affiliation - If you want to cut down on future leaks you might want to consider RSR Rocker Shaft Seals -
https://patrickmotorsports.com/products/eng91109910352
A small amount of Curil T on the valve cover seals will help prevent future valve cover leaks.

Earlydays

Also replace the power steering pump belt

Ubipa

Interesting upgrade adding some convenience to including sealing rings. Also ones that might not be prone to sheering on installation. Anyone use them?

https://www.neilbainbridge.com/Produ...ft-Sealing-Kit

koenig_roland

Well, ( :-) )
depends on how often you plan to remove the engine :-)
I have the 964`s since 15years and it was always a kind of mistery, to remove the engine when living downtown munich and frankfurt. Since i moved to an own house with a cosy garage 5 years ago, i removed the engines of my two 964 at least 4 times.. Quite easy and fast process now for me.
Back to your question: Fuel lines at the engine and from/to the tank. 30years old and for sure cracked... If you have time, you can use your old fluel lines, remove the hose by yourself from the fittings and ask a hose shop to crimp new hose on the OEM fittings. Did this with my two cars and it costs less than 100,- per car.. even the "long lines" can be re-done with the help of a hose shop. Have the fittings galvanisized before and it looks as good as OEM new for small money.
Next think for me would be clutch slave cylinder and the pressure hose. I also would removed (i did) or renew the insulation mat at the bulkhead.

Depending on the age, i would renew O2 sensor to a new high quality part (did this recently at my convertible and solved a slightly hesitating engine in the lower RRM range - the old sensor was perhaps 7 or 8 years old).
Back to hose (for me one of the weakest points of our old cars): would perhaps replace all oil hose from the engine to the filter, from the filter to the thermostat, to the cooler and the short ones around the tank. Did this in autumn at my convertible (and do this at the moment at my track Qpe)... i also changed the oil coolers, to have "fresh" and new stuff there... Imagine having in summer a tour with the car and seeing a "drip".. you have to disassemble everything i summer and crashed your tour..

Next thing i would check is the clutch. At least a new friction plate, i also did this with the old pressure plate in the past, .. is quite cheap... most important is the whole stuff of small bearings, around the clutch fork and perhaps the clutch fork itself.. This could transform your clutch to a "modern" car feeling, even if you have not thought about i yet... for me (!!!), the clutch mechanism should be checked and if its state is questionalbe renewed every time, the engine ist out... 100,- for the small parts bearings, plastik stuff and it is fresh again.. The fork itself was bent at my QPE once for example...
well, if you are in there.. you can ceramic coat the fan and the fan housing for not so much money (spend 300,- at a well know german engine builder for this), renew the starter and the alternator... the have perhaps 30 years and the contacts are not made for eternity...
And i would clean and recalibrate the injectors.. in germany, you can do this for roughly 180,- for the set and the check also the spray pattern.. on both of my cars, one injector was out of range and had to be changed... but this gave me a much smoother engine run and the cars start better when hot...

This all sound terrible, i know. But i have my two 964 since 15 and 10 years, do everything (besides the engine and the gearbox rebuilds) by my own and have never ever had an issue using the cars and quite seldom "something" during the summer season when i use the cars more or less daily...depsite going to roud-trips to the south of europe and tracking to blue QPE quite a lot and quite hard at the Nordschleife...

Another thing i had this year, because there was never attention from my side: the pressure hose from the power-steering in the convertible was dripping... Also not so expensive and if renewed once, you can forget it for the next 30 years...

It is the amount of small things that makes a good car in my opinion... Have fun! :-)