Good morning,Advice from senior members

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01 Sep 2011 07:59 #6055 by denhamfly
Brad and Stan I am still trying to figure out if my valves are bent. Would it be wrong to tow it close to one of these knowledgeable members that are offering there help for road side assistance and act like it broke down there? I am just asking?:p

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01 Sep 2011 09:24 #6056 by srshaw3
You would want to make sure they have a leakdown test kit, and the knowledge to use it first :rolleyes:

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01 Sep 2011 09:34 #6057 by denhamfly

You would want to make sure they have a leakdown test kit, and the knowledge to use it first :rolleyes:


I like the way you are thinking!

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01 Sep 2011 15:54 #6059 by 928mac
Oscar, refresh my memory, what kind of mechanical skill do you have?
none, little, lots?

Because if it is none, then yes you should have someone else do the work.
If you have ever changed a water pump, timing belt or chain or things like that, then we can walk you through removing and installing the heads.

Let me know how comfortable you feel with working on it and would you have enough tools?

You could always get close to Stans house and phone him :rolleyes: he he he

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01 Sep 2011 16:09 #6062 by srshaw3
Louisiana is a long way away.....
As some know, I struggle to find time to work on my own projects :(

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02 Sep 2011 08:15 #6064 by denhamfly
Brad, I can work on tractors, pecan pickers, Chevy V-8’s, gas chromatographs, sailboat engines and transmissions, four wheelers. Motor cycles and outboard motors.
This car has always kicked my ass. I am not a hundred percent sure it is the valves yet. It was doing this years ago and it was, because of a disc on the flywheel that was slipping that made it impossible to time. Have you ever heard of that problem before? Ether one of the above problems are a pain, I just need to get off of my behind and figure out which one. Is there an easy way to diagnose bent valves?

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02 Sep 2011 13:45 #6065 by 928mac
A leak down test and or a compression test
ILL see if I can find a step by step link.

leak down link
en.wikipedia.org/wiki/Leak-down_tester

www.motorcycleproject.com/motorcycle/text/leakdown.html

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02 Sep 2011 21:40 #6075 by pcar928fan

gas chromatographs


REALLY?! What the hell for?! I have used them many times, but never worked on one!

James
78 Silver / Black-white #295
84 Ruby Red / Black AO84
88 Dark Blue / Linen-Black
92 Polar Silver / Dark Blue 92EURO
93 Arrow Blue / Black

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03 Sep 2011 08:49 #6082 by Kiln_Red

This car has always kicked my ass. I am not a hundred percent sure it is the valves yet. It was doing this years ago and it was, because of a disc on the flywheel that was slipping that made it impossible to time. Have you ever heard of that problem before? Ether one of the above problems are a pain, I just need to get off of my behind and figure out which one. Is there an easy way to diagnose bent valves?


Look at the belt via one of the peep holes in the TB covers. That will tell you whether the belt broke which would almost certainly result in bent valves.

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03 Sep 2011 09:01 #6083 by srshaw3

because of a disc on the flywheel that was slipping that made it impossible to time. Have you ever heard of that problem before?


As I recall there is a sensor near the top of the flywheel cover that senses a wider gap in the flywheel for timing purposes. I can't think of a "disc" that could slip to cause an issue, but I certainly don't know everything. The sensors are a common failure part, due to age as I understand.

Brad's suggestion on checking under the timing covers is a good one. I would suggest removing the passenger side cover to review the timing belt tension as well, since technically it could remain intact but still slip a tooth or two and result in bent valves as well. As Brad suggested usually it is a complete failure of the belt that causes the valves to bend, often because of the water pump bearing failure.

I am definitely a fan of Ed's replacement water pump that includes a larger bearing but also isolates a bearing failure from the timing belt, so a water pump failure is just that, not also a bent valve issue.

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03 Sep 2011 09:09 #6084 by Kiln_Red
Stan, like you, I can't make sense out of the slipping flywheel symptom either. :confused:

Perhaps the portion of the flywheel that the CPS (Crankshaft Position Sensor) picks up on was damaged or broken off.

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03 Sep 2011 09:25 #6085 by srshaw3

Stan, like you, I can't make sense out of the slipping flywheel symptom either. :confused:

Perhaps the portion of the flywheel that the CPS (Crankshaft Position Sensor) picks up on was damaged or broken off.


I actually probably should have said "timing ring" as I think it is better known as that. The timing ring is only pressure fit to the flywheel as I recall, and can be removed if needed. It just wouldn't seem terribly likely that it would slip.

I had my '90 GT converted from the single disc clutch to the older, and stronger, dual disc clutch. Swapping the timing rings from an S4 automatic to the S flywheel was part of the process, so I do know they can be changed.

As I recall the process of swapping timing rings is usually performed by heat and cold.

Wow, the thought just occurred to me, I wonder if any of my car symptoms could be related to a slipping timing ring. My first thought is that timing would show up as wrong, since a slipped timing ring would cause the plug to fire when the piston was in the wrong position....

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03 Sep 2011 09:49 #6086 by srshaw3

Wow, the thought just occurred to me, I wonder if any of my car symptoms could be related to a slipping timing ring. My first thought is that timing would show up as wrong, since a slipped timing ring would cause the plug to fire when the piston was in the wrong position....


But then I recall that the car has run well for some periods of time, which could only be true if the timing ring was in the correct position, so it would need to be moving back and forth from good to bad positions. I will check the timing anyways...

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04 Sep 2011 01:21 #6091 by Kiln_Red
I would think that an issue with the timing ring would be highly unlikely in your situation because of the intermittent running issues. What kind of shape is the exhaust in on your car? I had a bad exhaust leak before the o2 on my car that led to strange intermittent running issues for awhile.

Concerning timing rings, I don't think the earlier 928s have one. Or maybe I've just never noticed it. :confused:

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04 Sep 2011 06:13 #6093 by srshaw3
Non known issues with the exhaust, when I review more, I will update my thread.

I believe I have the flywheel for my '80 on the floor and it is toothless (no ring). It also had a distributor you could turn to set timing :)

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05 Sep 2011 09:00 #6117 by denhamfly

I actually probably should have said "timing ring" as I think it is better known as that. The timing ring is only pressure fit to the flywheel as I recall, and can be removed if needed. It just wouldn't seem terribly likely that it would slip.

I had my '90 GT converted from the single disc clutch to the older, and stronger, dual disc clutch. Swapping the timing rings from an S4 automatic to the S flywheel was part of the process, so I do know they can be changed.

As I recall the process of swapping timing rings is usually performed by heat and cold.

Wow, the thought just occurred to me, I wonder if any of my car symptoms could be related to a slipping timing ring. My first thought is that timing would show up as wrong, since a slipped timing ring would cause the plug to fire when the piston was in the wrong position....


Check, the ring had 2 experts change every electronic part on my car. It would run good and then run like crap. Brought it to a guy in New Orleans he went right to the fly wheel and showed me it was slipping. It is pressed on he put a tack on it but told we it might not hold because they are two different kinds of metal. He had my car running in less than a day. The other people chased there tail for a year and cost me $2000 in parts,

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05 Sep 2011 09:05 #6118 by denhamfly

A leak down test and or a compression test
ILL see if I can find a step by step link.

leak down link
en.wikipedia.org/wiki/Leak-down_tester

www.motorcycleproject.com/motorcycle/text/leakdown.html


I have a compression tester, thanks for the procedure, now I just have to get off of my behind and do it.

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06 Sep 2011 02:16 #6125 by srshaw3

It is pressed on he put a tack on it but told we it might not hold because they are two different kinds of metal. He had my car running in less than a day. The other people chased there tail for a year and cost me $2000 in parts,


Did he just drop the clutch cover to find this? Could the timing ring be rotated by hand without the flywheel moving? If so, I think this is what I will look at next. My problems started 3+ years ago, after having a number of projects done to ensure it was a reliable daily driver (ironic eh?), the clutch conversion was one of those projects.

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06 Sep 2011 07:49 #6127 by denhamfly

Did he just drop the clutch cover to find this? Could the timing ring be rotated by hand without the flywheel moving? If so, I think this is what I will look at next. My problems started 3+ years ago, after having a number of projects done to ensure it was a reliable daily driver (ironic eh?), the clutch conversion was one of those projects.


He did drop the clutch cover it could be moved by hand but, barley he said it moves easier when the fly wheel heats up. If you think you might have that problem I would put a mark on it and the fly wheel and run it hard and see if the lines remained the same. This guy used to work at the Porsche dealership he said it is a common problem that many people end up spending a lot of money on going down the wrong path. Before I brought it to him it was at the dealership they got me to buy a lot of new parts that did not fix the problem.

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06 Sep 2011 14:47 #6128 by denhamfly

REALLY?! What the hell for?! I have used them many times, but never worked on one!


The things people do for money!!

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06 Sep 2011 17:43 #6135 by pcar928fan
I prefer to sell drugs for money! MUCH more fun than using lab gear!!! ;)

James
78 Silver / Black-white #295
84 Ruby Red / Black AO84
88 Dark Blue / Linen-Black
92 Polar Silver / Dark Blue 92EURO
93 Arrow Blue / Black

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07 Sep 2011 08:13 #6144 by denhamfly

I prefer to sell drugs for money! MUCH more fun than using lab gear!!! ;)


Hopefully legal ones.:eek:

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07 Sep 2011 18:32 #6154 by pcar928fan
Yea, for the most part! LOL! Symbicort and Vimovo right now...

James
78 Silver / Black-white #295
84 Ruby Red / Black AO84
88 Dark Blue / Linen-Black
92 Polar Silver / Dark Blue 92EURO
93 Arrow Blue / Black

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07 Sep 2011 23:33 #6159 by 928mac
Ahhh I want the blue pill :eek:

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08 Sep 2011 07:53 #6161 by denhamfly

Ahhh I want the blue pill :eek:


Watch it someone might get an eye put out!

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08 Sep 2011 17:20 #6172 by pcar928fan
^^^^^
lol!

James
78 Silver / Black-white #295
84 Ruby Red / Black AO84
88 Dark Blue / Linen-Black
92 Polar Silver / Dark Blue 92EURO
93 Arrow Blue / Black

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