Interference engines

[gwl123]

Just spoke with a very good mechanic that does work on 928's and he said that 2v cars are no different than 4v ones. If going 50mph and the belt breaks there would still be valve damage. He said to keep the 911 and discourage the 928.

[dcrasta]

He is wrong.
Very different cars, From the toothed belts they use, to the tension on the belt, to the consequences of breaking belts. Tell him to stick to 911's and find someone else. You're in MD and there are a lot of good 928 people in MD.

Ditch the zero (bigoted against 928s)

[MPDano]

There are some late 16v Euro Engines that may crash valves, but for the most part that answer would come from the 911 mechanics who dislike us

I have a 1981 and a 1983 16V and both are NON-interference Motors.

[MPDano]

Also, if you do get a 928, run from that mechanic that gave such advice. We're all you need.

[gwl123]

He does work on many 928's and has a great reputation so.......

[gwl123]

What shops do work on 928's in Maryland?

[MPDano]

Originally Posted by gwl123

He does work on many 928's and has a great reputation so.......

Umm, then maybe we all need to know where this 928 mechanic is located so we can...

[dcrasta]

GWL123 >

~Other people may trust him to work on their cars, but someone that says '2v cars are no different than 4v ones' has demonstrated a very fundamental lack of experience and understanding with 928s.

He may be a decent general mechanic, and even a great 911 mechanic, but he doesn't know 928s'

[neil30076]

Originally Posted by gwl123

Just spoke with a very good mechanic that does work on 928's and he said that 2v cars are no different than 4v ones. If going 50mph and the belt breaks there would still be valve damage. He said to keep the 911 and discourage the 928.

I have had the belt 'go' on my 81 twice since i bought it from new - and no damage. He is wrong. To get valve damage the piston needs to collide with the valves, and it ain't going to happen on the 16v non interference engines.

[gwl123]

Great I'll limit my choices to an '83/84. Reading thru the board and other sites there seems to be a lot to look at with the issues. The water pump and electricals are my main concerns. Is there a thorough checklist written to address?

[Landseer]

You were right earlier.
Keep the 911.
Unless you like DIY with a high puzzle component.
( and based on this post you made, that is unlikely: Can anyone recommend an honest garage in Wash. D.C.? I need a minor tune-up for my '76 911.)


Obviously whatever mechanic you settled upon isn't 928-worthy.
The only ones that are have extensive and repetitive 928 knowledge.

Also, to make a selection based on interference vs non-interference is odd.
Both versions of the vehicle get the same maintenance.
Neither should EVER suffer from a belt mishap.
Unless you are intending to buy and not maintain.
If that's true, no 928 needs you.

[MPDano]

Originally Posted by gwl123

Great I'll limit my choices to an '83/84. Reading thru the board and other sites there seems to be a lot to look at with the issues. The water pump and electricals are my main concerns. Is there a thorough checklist written to address?

Try this thread as there are a lot of issues that have been addressed and fixed there. 83 and 84 are great years See above wavy dude in my Signature.

**MOST Common 928 Issues AND Fixes**

[Danglerb]

Originally Posted by gwl123

He does work on many 928's and has a great reputation so.......

Mechanics that don't really know the 928 can be very expensive in the long run.

I stopped in a shop once that had some parts listed on Craigslist, and the owner was working on a 928 and and real proud of it. He just replaced a windshield for like $2,000 and was telling me how it was only available from the dealer. I told him a dozen of us locally just had genuine Sigla glass put in for $300 installed. His ignorance cost his customer $1700 and I am pretty sure that was the tip of the iceberg.

[924CarreraGTP]

Your mechanic needs to do a little research on the cost of repairing a 911 engine when the trashy timing chain tensioners fail.
The 928 is a better vehicle by leaps and bounds. I know because I own both of them but guess which one I chose to build a street racer out of?
The U.S.16V 928s only interfere if they have had larger cam grinds or excessive amounts of carbon build up. The stock U.S. 16 valves shouldn't interfere otherwise. Run Barryman's B12 chemtool through your gasoline in small amounts to blow out the carbon, and keep your timing belt serviced (tensioned) and it won't be a problem.
Also, install tensioner stops on your 911 timing chain tensioners or kiss that 6 cylinder VW goodbye too. lol
I'm sick of people being down on the 928. The cars were assembled right beside the 911s by the same people. The only difference is prewar combustion technology in the 911 verses premium combustion technology in the 928.
Years ago a mechanic I now work with told me all the 928 engines interfere. I said then "I believe its just the 32 valves". He later agreed with me. I have a chance right now to buy a 32 valve 928S cheap, but I don't want it because it is an interference engine. After sweating long and hard over my 911 and many 944s, I think I'll stick to the '83, '84 928s.

[gwl123]

I'm still interested in a 928S. I can do some DIY work except for the timing and waterpump. I will let the expert handle that since its one long belt that turns everything. As for the carbon build-up hmmm.....will Seafoam ($10) also work? I don't think my mechanic was dissing the 928. He was just warning me of more expensive maintenance. Parts are plentiful for now and cheap as I come across many for sale on craigslist. Just doing some homework first.......

[harborman]

I don't think the "interference engine" is peculiar just to Porsche. Don't a number of new cars also have these engines?

[MPDano]

Originally Posted by gwl123

I'm still interested in a 928S. I can do some DIY work except for the timing and waterpump. I will let the expert handle that since its one long belt that turns everything. As for the carbon build-up hmmm.....will Seafoam ($10) also work? I don't think my mechanic was dissing the 928. He was just warning me of more expensive maintenance. Parts are plentiful for now and cheap as I come across many for sale on craigslist. Just doing some homework first.......

You can easily do this yourself. We've covered all this in this forum. Get the parts and tool and we'll guide you through it. You literally can do this in an afternoon. The only real time used will be all the cleaning.

[Pete R]

Originally Posted by harborman

I don't think the "interference engine" is peculiar just to Porsche. Don't a number of new cars also have these engines?

I think just about every engine now is probably interference. All the manufacturers are trying to increase compression to get the gas mileage. I have an Escort we are making into a Lemons car and THATS interference.. not really a good way to pick a vehicle.

[MPDano]

My Mitsubishi Eclipse Turbo "IS" Interference and makes doing a Timing Belt on a 928 a cake walk. The Mitsu also requires a Balancer Belt besides the Timing Belt PLUS the Oil Pump Gear MUST be be on time. Seriously, a 928 TB/WP Changeout is like putting a Rubberband on versus the Mitsu.

[neil30076]

+928 ^^^
My daughters Xterra needed a timing belt - its interference as well, and it is a major dis-assemble vs. a 16v non interference 928.
A 32v 928 needs more care, but not that much more difficult.