928 Block Damaged by Water Pump Repair
03-09-2012 | 01:45 PM
#151
Rennlist Member
Joined: Apr 2006
Posts: 35,700
Likes: 503
The stock tensioner should hold oil just fine after a rebuild. The gasket is a chore to get right and I've seen punctures in new boots made while re-installing the tensioner. I learned the hard way and have had to redo them. Then, of course, there is the washer, usually missing, on the end of the low-tension warning spring. Did you find that there or missing?
03-09-2012 | 02:56 PM
#153
Thread Starter
Former Vendor
Joined: Feb 2005
Posts: 15,230
Likes: 2,489
From: Anaheim
Dan,
I agree with you regarding the oil in the tensioners. Replaced the tensioner on my '94 last month with the Porken model. A very accomplished east coast 928 repairer had never done one, so worked with me on it. He has probably done ~100 timing belt jobs in the past dozen years, and always rebuilds the tensioners. I asked him how many of the tensioners were full of oil (or even had a significant amount of oil) when he removed them. He said less than 10% had any significant oil, and probably only 1 or maybe 2 had seemed to be full of oil (excluding his own GT). My OE tensioner had been rebuilt 6 years ago when we pulled the engine and redid everything after I'd bought the car. It had about half as much oil as it should have (and was full when we did the job 6 years ago).
So - I've concluded that probably 90+ percent of all 928's out there (excluding those cars whose members are active on the 928 Forum of course!) have tensioners that are NOT functioning as designed. That is one major reason why I think the Porken tensioner is an upgrade for most 928's.
By the way, that "fluid pump" for the 911's that doesn't fail - it's an oil pump, as those engines are about equally cooled by oil as air!! And, of course essentially ALL so called air cooled 911 engines leak oil.
Cheers all, and thanks to Greg for developing such a great solution for water pump impeller incursion into the block.
Gary--
I agree with you regarding the oil in the tensioners. Replaced the tensioner on my '94 last month with the Porken model. A very accomplished east coast 928 repairer had never done one, so worked with me on it. He has probably done ~100 timing belt jobs in the past dozen years, and always rebuilds the tensioners. I asked him how many of the tensioners were full of oil (or even had a significant amount of oil) when he removed them. He said less than 10% had any significant oil, and probably only 1 or maybe 2 had seemed to be full of oil (excluding his own GT). My OE tensioner had been rebuilt 6 years ago when we pulled the engine and redid everything after I'd bought the car. It had about half as much oil as it should have (and was full when we did the job 6 years ago).
So - I've concluded that probably 90+ percent of all 928's out there (excluding those cars whose members are active on the 928 Forum of course!) have tensioners that are NOT functioning as designed. That is one major reason why I think the Porken tensioner is an upgrade for most 928's.
By the way, that "fluid pump" for the 911's that doesn't fail - it's an oil pump, as those engines are about equally cooled by oil as air!! And, of course essentially ALL so called air cooled 911 engines leak oil.
Cheers all, and thanks to Greg for developing such a great solution for water pump impeller incursion into the block.
Gary--
I have virtually no problems with the factory tensioner, which is why I still use it.
03-09-2012 | 03:02 PM
#154
Thread Starter
Former Vendor
Joined: Feb 2005
Posts: 15,230
Likes: 2,489
From: Anaheim
The stock tensioner should hold oil just fine after a rebuild. The gasket is a chore to get right and I've seen punctures in new boots made while re-installing the tensioner. I learned the hard way and have had to redo them. Then, of course, there is the washer, usually missing, on the end of the low-tension warning spring. Did you find that there or missing?
I think that washer is 928 engine 100.
That's the intro course to being able to open the hood.
Of course, I also though that putting in the "key" for the oil pump gear was something very basic, but I just took apart an engine from one of the "infamous" 928 engine builders that didn't have one....but the nut was tightened enough to keep the gear from spinning on the shaft....perhaps a "trick" weight saving idea?
