Show full size 924Board.org
Discussion Forum of 924.org
 
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 
 Technical FAQ924 FAQ (Technical)   Technical924 Technical Section   Jump to 924.org924.org   Jump to PCA 924 Registry924 Registry

Timing Belt

 
Post new topic   Reply to topic    924Board.org Forum Index -> 924S Discussions
View previous topic :: View next topic  
Author Message
afenn  
Guest





PostPosted: Thu Jul 04, 2002 3:05 pm    Post subject: Reply with quote

Does anyone have experience using the low end after a timing belt failure? I just lost my timing belt do to a defective water pump, I bent all four exhaust valves and scored the pistons. Any help would be appreciated.

Andrew
Back to top
Paul  
Guest





PostPosted: Fri Jul 05, 2002 12:52 am    Post subject: Reply with quote

Ouch, I feel your pain...

I'm not a professional mechanic anymore, but I have been playing one at home for 30 years.

If the pistons don't have cracks or holes, most of the time you're ok.

If the engine has high miles or has had low oil pressure that might indicate worn main and rod bearings, I would drop (or lift) the engine and replace pistons and bearings.

Or I might be tempted to find a 968 motor....
Back to top
Porschephile  
Guest





PostPosted: Fri Jul 05, 2002 3:37 am    Post subject: Reply with quote

I have a 968 motor...unfortunatley, It's not in the 924S... it's in the 968. but one of these nights when dad is asleep, he may wake up to a severly underpowered 968...

Anyway, That REALLY sux about the timing belt. I would be soooo pissed. just outa curiosity, is it an aftermarket belt, or a Porsche genuine product? I hear aftermarkets will fail often. anyway, just so ya know, Porsche dealers may have a 10% discount on Parts and labor for PCA members. good luck, and I hope all goes well for ya.
Back to top
gohim  
Guest





PostPosted: Fri Jul 05, 2002 4:20 am    Post subject: Reply with quote

How old was the water pump, and how long was it since you replaced the belts, pulleys and front oil seals.

Water pumps do die, and that's why it is recommended that you replace the other related parts when you are in there doing the belts.

The engine that I am working on to replace the broken block in my 924S also had a water pump failure. But it looks like it was the fault of the owner of the car. Looks like there was a head gasket leak, and the owner poured in some cooling system stop leak. I found the stuff everywhere, and it looks like it caused the waterpump to seize. Now maybe the pump was already leaking, but it doesn't look like it, just looks like the stop leak stuff made the pump go zero clearance, and seize, breaking the belt, and causing the usual damage.

If the engine has less than 100K, and the pistons tops don't look bad, I would consider having the head serviced, and bolting it back onto the block.

The engine that I am freshening up has about 120K, and shows some wear in the cylinder bores, but should be okay. The bearings are all still tight, but I am going to replace them since I am already in there.
Back to top
afenn  
Guest





PostPosted: Fri Jul 05, 2002 9:48 pm    Post subject: Reply with quote

The engine has 106000 miles on it and the water pump is three months old (new not rebuilt) as well as the belts. I'm using a 160 deg. thermostat in the car and the shaft seized while I was dropping a VTec Prelude. I'm using the Zerex for aluminum blocks and tensioned the new belts to the correct spec using the 944 tensioner and retensioned a month ago. When I replaced the belts and water pump I also replaced all of the pulleys.
This is an 84 944 and now that I'm looking at the pistons and considering dropping my 924s motor in. The cylinder walls are not scored and mic out perfect but the valves have a nice glimmer on the portions that contacted the pistons so I'm worried more about the rod bearings since the valves rounded the piston indentations nicely.

Thanks in advance

Andrew



[ This Message was edited by: afenn on 2002-07-05 21:49 ]
Back to top
gohim  
Guest





PostPosted: Sat Jul 06, 2002 3:29 am    Post subject: Reply with quote

What brand was the water pump that you used? Was it a Geniune Porsche, or one of the aftermarket ones like the LASCO? I am concerned because I have a LASCO sitting here, and it does not appear to be as well made as the Porsche Original Pumps are.

The bottom end is usually not damaged when the belts break, slight marking on the piston top/s is normal in the case of a belt failure problem. With 106K miles on the block, I would probably have the head serviced, if it was not severely damaged, and take the time while the head is at the machine shop to drop the oil pan and replace the rod bearings. You can get the rod bearings for around $50, and a block gasket set is only $75-$100.

If you were to drop a 924S engine into an 84 944, you would get a power boost from the revised piston top design, and increased compression, but you would have to decide whether to modify the 84 to use the 924S wiring harness, ignition electronics, and fuel lines, or take the wiring harness, DME, and fuel rail stuff from the 84.

And which set of crank sensors would you use?



[ This Message was edited by: gohim on 2002-07-06 03:33 ]
Back to top
afenn  
Guest





PostPosted: Mon Jul 08, 2002 11:58 am    Post subject: Reply with quote

Gohim: the water pump on the 944 was a Porsche OEM. I have a Lasco on the 924 motor and have had no issues except that I did have to replace it because it leaked at the spindle after 6 months but the replacement has had no issues over the last three years.

I'm going to attempt to use the 924s crank sensors if they fit the 944 harness. I don't see Porsche making different sensors only de-tuning the engine with the different brain.

I'm pretty anxious to get back driving the car so I'll take my chances with the 924s engine swap.

Thanks

Andrew


[ This Message was edited by: afenn on 2002-07-08 12:02 ]
Back to top
Display posts from previous:   
Post new topic   Reply to topic    924Board.org Forum Index -> 924S Discussions All times are GMT + 10 Hours
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group