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While the government are advising to stay at home i finally got around to putting the original leather rear quarter pannels in, the ones i straightened in the above post.
Was also lucky to have a spare new seat belt surround as the old one just fell off when i removed that small section of trim
am very happy with the results but i did not take many pictures, just showing the before =no stitching, compaired to the original leater ones = stitching
Have never seen a securing clip like the one pictured, i guess its not a factory thing
Great improvisation on the clip - it worked did it not.
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Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission? George Layton March 2014
928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
Just starting to do the head gaskets on the old girl and i think i might also need a new coil, one of the few things i have not replaced
might even splash out on a new coil lead )
Your cam sprocket photos are interesting in that from memory that is the first time I have seen signs of belt contact in the bottom of the valley. Wear is invariably on the top flats that one might think should be the last place to exhibit wear given the drive thrust load is supposedly taken by the teeth engaging the valley. Obviously there is a sinusoidal cyclic activity going on here but even so the coating on the flats has gone whereas the coating within the valley and its wall is barely abraded.
I have often wondered whether this is a sign of too much belt tension as in a belt that has been tightened according to procedure wherein the specified tension is simply "too tight". Why else would the flats invariably fret first? If the coating within the valley is not disturbed does this imply that the belt is not fully "run in"?
When investigating toothed belt design I found something very interesting on the Gates website wherein there are specific design clearances required for the transition from tooth to top flat of the belt. This feature seems to ensure the edges of the tooth do not wear but yet the flats do in the case of the 928 sprocket. This makes me wonder if this wear pattern is something unique to the 928 or whether "they all do it".
Either way those sprockets obviously need re-coating or replacing.
sorry for the delay gents but have been a bit busy with the headgaskets.
As to the belt tesion Fred, its had a porkensioner on for the last 5 years but have no service history for the first 27years and 140k miles, but i have a pair of good used ones to fit.
so when i drained the coolant from the block drains, nothing came out of the left bank as looking from the front of the vehicle, did not think much about it untill i removed the head and found most of the headgasket on thant bank had just disintegrated and made a thick sludge which had blocked the drain.
once the head was stripped and cleaned the depth of the cavitation/ corrosion of the head can be seen but luckily nothing had actually got past the fire ring of the headgasket, and the other bank was nowhere near as bad.
over the last 18 months of driving i had seen the temp gauge start to creep up to just over the last white mark on the gauge, intermittently and at any engine speed, and then would drop back down again, it never used any water, but i guess it was a lack of, or incorrect water circulation.
Now these old girls are well, getting old, head gasket/ over heating problems will become more and more common, if the gaskets are still original
bought 32 new VSOS and very luckily for me i had a spare new one from another rebuild -nobody is perfect when fitting them
one question:
once i cleaned all the valves, they all lapped in well appart from an end exhaust seat - pictured- it did eventually get a nice even seal on the seat but took a lot of lapping, any reason why? slight warp of the seat?
After much cleaning of the heads and valves etc, new lifters and cam chain + all the rubber bits, the heads are now back on, the rest of the block is now clean and all other seals on the entire engine have been replaced so fingers crossed it should be leak free.
intake is now on, cambelt is next then just a few pieces left before it gets refitted to the car
cam pictures for Mr CS.
sorry for the delay gents but have been a bit busy with the headgaskets.
As to the belt tesion Fred, its had a porkensioner on for the last 5 years but have no service history for the first 27years and 140k miles, but i have a pair of good used ones to fit.
so when i drained the coolant from the block drains, nothing came out of the left bank as looking from the front of the vehicle, did not think much about it untill i removed the head and found most of the headgasket on thant bank had just disintegrated and made a thick sludge which had blocked the drain.
once the head was stripped and cleaned the depth of the cavitation/ corrosion of the head can be seen but luckily nothing had actually got past the fire ring of the headgasket, and the other bank was nowhere near as bad.
over the last 18 months of driving i had seen the temp gauge start to creep up to just over the last white mark on the gauge, intermittently and at any engine speed, and then would drop back down again, it never used any water, but i guess it was a lack of, or incorrect water circulation.
Phil,
An interesting post that I will expand on progressively.
First of all a couple of quetions:
1. What [if anything] did you do to remove the corrosion on the heads?
2. How did you deduce you had an overheating problem - presumably you saw a "higher than normal" temperature indicated on the dash panel gauge but how high?
Horrible as they were, I did not see anything on the photos that immediately suggests why you would have had a cooling issue that showed on the dash panel gauge and would politely suggest you further investigate to find out why such happened if the root cause has not been eliminated. Maybe the radiator has a partial blockage given the crud that was floating around? - perhaps you can reverse flush the thing.
The photos of the gasket damage tell their own story. I dare say you are aware but just in case- as best I can tell the coolant flow path is such that coolant enters the volute around the cylinders from the front of the engine, duly flows to the back of the volute and then enters the cylinder head passages though the ports at the back of the heads. If you study the flow ports in the head you will see that there are significant flow ports around each cylinder but the head gasket openings do not correspond directly with the head gasket that has some small holes adjacent to those ports but are way smaller. I presume these holes exist to ensure there are no air pockets trapped around the top of the cylinders but due to small size ensure thre is little flow. Now take a look at the state of the gaskets that were in there. They have been completely eaten away [I will discuss why in another post shortly] . When the gasket is eaten away it exposes the underlying port fully and thus more coolant will flow through said ports and thus coolant flow to the rear cylinder location will be [significantly?] reduced. You said the damaged valve was at the end but not which end- my guess is that it was an exhaust valve at the back of the engine. Because of the rogue flow diversion, the rear cylinder was overheating to some extent and the hottest part being the exhaust valve seat has thus taken some attrition- sound feasible? This may explain the valve seat attrition but not why you saw an overheating issue if suggested by the dash panel gauge.
Regarding the cam sprocket wear I do believe there may be a fundamental design issue that causes this wear pattern that I believe should not happen but invariably does. Whether or not the PKT improves this wear pattern I have no idea but by now someone somewhere should have some thoughts on this given the time they have been around. The tensioner configuration may be different but the job it has to do is the same as the stock tensioner.
sorry for the delay and thanks for the detailed reply Fred
the corrosion was removed with a sharp scraper and 180/280 grit paper and a sanding block
As to the cooling side, i have fushed the radiator and only a very small amount of dirt/debris came out, it has had a new theremostat + its rear seal and will be getting a fresh water pump.
As i reassemble it everthing looks good so will closely monitor and report back.
The marks on the block where the waterpump sits cannot be felt with the finger nail test
I found a good source of blue "omega" clips from this side of the pond at https://www.bresco.com/ - no connection just happy with their range of products for older cars
and the picture of the wiring loom overspray was fixed with heatshring tubing over the original loom.
life is getting in the way of the rebuild so might be next week before i get back to it
Picture is of the first securing bracket next to the power steering resovoir going to the cooler line.
Over the years of spilled oil when topping up and recent slight leak from the rubber pipe, the rubber part of the bracket has swelled up .
Would it be the swelling of the rubber have caused the platic to split as it has?
The other rubber pictured is a second hand one i had, but that had to be trimmed down to make it fit
Thanks to Roger it now has a new rubber cover over a working oil level sensor
And the engine is all built up, clean and ready to fit
04-05-2020, 04:24 PM
George Layton March 2014
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