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My third 924 is a 931 restore thread
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jason c  



Joined: 13 Jan 2014
Posts: 1018
Location: Nwi

PostPosted: Sat Jul 25, 2015 8:50 am    Post subject: Reply with quote

I have done this and many other chassis repairs many times.
I think the zinc factor is overrated. In order to weld, you'll need to remove the zinc from the metal by grinding it down, the metal needs to be clean anyway. You can wear a breathing system if your really worried about breathing the zinc or run a small fan on to push the fumes away as you weld. There shouldn't be much fumes if youve cleaned the metal well.
You will have trouble welding it if its not clean.
A mig welder makes a pretty good mess of the metal, flux core doesn't help. It will tend to want to blow through on start up. You can help the starting by having a thicker scrap piece of metal next to your work to start on. You can also use a copper backer to help.
If your not going to remove the carpet (highly recommended) you can put down a welding blanket, the slag generated can and will burn through it, you'll need it folded in several layers.

I always prime with a chromated epoxy. It does an excellent job of protecting the metal where the zinc was removed.
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Han Solo  



Joined: 11 Jul 2015
Posts: 234
Location: Lebanon TN

PostPosted: Sat Jul 25, 2015 9:35 am    Post subject: Reply with quote

jason c wrote:
I have done this and many other chassis repairs many times.
I think the zinc factor is overrated. In order to weld, you'll need to remove the zinc from the metal by grinding it down, the metal needs to be clean anyway. You can wear a breathing system if your really worried about breathing the zinc or run a small fan on to push the fumes away as you weld. There shouldn't be much fumes if youve cleaned the metal well.
You will have trouble welding it if its not clean.
A mig welder makes a pretty good mess of the metal, flux core doesn't help. It will tend to want to blow through on start up. You can help the starting by having a thicker scrap piece of metal next to your work to start on. You can also use a copper backer to help.
If your not going to remove the carpet (highly recommended) you can put down a welding blanket, the slag generated can and will burn through it, you'll need it folded in several layers.

I always prime with a chromated epoxy. It does an excellent job of protecting the metal where the zinc was removed.


All good tips. Thanks for the heads-up on the carpet. I've done a lot of welding on 914 sheet metal which appears to be thinner than this area. I'm a big fan of weld through primer. Bottom line, this car probably won't see much rain while I own it but having that area fixed, sealed and painted is the way to go.
_________________
-----HAIRY ANT NEST RACING-----
Collecting, racing and restoring Porsches for fun and negative cash flow.
-----Epic 914 race car build----- http://forums.pelicanparts.com/porsche-914-914-6-technical-forum/767721-yet-another-rescue-porsche.html
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jason c  



Joined: 13 Jan 2014
Posts: 1018
Location: Nwi

PostPosted: Sat Jul 25, 2015 11:23 am    Post subject: Reply with quote

Han Solo wrote:
jason c wrote:
I have done this and many other chassis repairs many times.
I think the zinc factor is overrated. In order to weld, you'll need to remove the zinc from the metal by grinding it down, the metal needs to be clean anyway. You can wear a breathing system if your really worried about breathing the zinc or run a small fan on to push the fumes away as you weld. There shouldn't be much fumes if youve cleaned the metal well.
You will have trouble welding it if its not clean.
A mig welder makes a pretty good mess of the metal, flux core doesn't help. It will tend to want to blow through on start up. You can help the starting by having a thicker scrap piece of metal next to your work to start on. You can also use a copper backer to help.
If your not going to remove the carpet (highly recommended) you can put down a welding blanket, the slag generated can and will burn through it, you'll need it folded in several layers.

I always prime with a chromated epoxy. It does an excellent job of protecting the metal where the zinc was removed.


All good tips. Thanks for the heads-up on the carpet. I've done a lot of welding on 914 sheet metal which appears to be thinner than this area. I'm a big fan of weld through primer. Bottom line, this car probably won't see much rain while I own it but having that area fixed, sealed and painted is the way to go.


I've used the weld-thru primer, I'm not a fan. It doesn't have any bite, it scratches off easy & remains solvent sensitive.
I've plenty of welding on 914s as well. They were made with a different type of steel & were not galvanized.

Mig welders tend to have a larger output at startup, that initial bust is what tends to blow holes.
I prefer to tig weld patch panels. Less heat & warpage, better weld quality and easier to metal finish. Its expensive though.
Its a slower welding process but if you consider all the time youll spend grinding mig welds smooth, it not far off. If you're welding in metal that's needs to have a factory finish (you can't tell the repair has been done), tig is the best.
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Han Solo  



Joined: 11 Jul 2015
Posts: 234
Location: Lebanon TN

PostPosted: Sun Jul 26, 2015 8:53 am    Post subject: Progress and new parts Reply with quote

Excellent weather this morning for working in the garage. I got a nice package of new parts and I'm ready to get the water pump and timing belt changed. I noted that the combo bracket that holds the coolant reservoir and AOS was corroded so I pulled that, wire brushed to clean metal, primed and painted with enamel. I did the same to the coolant cross-over pipe. The chassis under the bracket was dirty but no rust. I love working on a galvanized car! Getting that water pump on was a struggle with the coolant pipes and that turbo oil supply pipe. Tight fit for sure. Of course I had the crank at TDC and noted that the timing mark on the cam was at 9 o'clock, odd. So I put my own mark on the back of the sprocket at the pointer. Bottom line, the car is running okay so the timing must be right. Anyway, I got the timing belt on and installed a new tensioner pulley. So I fabricated a spanner with a bar that I drilled two 1/8" holes, a couple of trimmed off nails and welded them to the back. Worked great! Then I started putting everything back together but left the timing belt cover off for now. I want to keep an eye on things till I get the engine sorted. I also welded up a crack in the cover, stripped and painted it also.














_________________
-----HAIRY ANT NEST RACING-----
Collecting, racing and restoring Porsches for fun and negative cash flow.
-----Epic 914 race car build----- http://forums.pelicanparts.com/porsche-914-914-6-technical-forum/767721-yet-another-rescue-porsche.html
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Fasteddie313  



Joined: 29 Sep 2013
Posts: 1497
Location: Not Detriot - NMI

PostPosted: Sun Jul 26, 2015 9:52 am    Post subject: Re: Progress and new parts Reply with quote

Han Solo wrote:
Of course I had the crank at TDC and noted that the timing mark on the cam was at 9 o'clock, odd. So I put my own mark on the back of the sprocket at the pointer. Bottom line, the car is running okay so the timing must be right. Anyway, I got the timing belt on and installed a new tensioner pulley. So I fabricated a spanner with a bar that I drilled two 1/8" holes, a couple of trimmed off nails and welded them to the back. Worked great! Then I started putting everything back together but left the timing belt cover off for now. I want to keep an eye on things till I get the engine sorted.




The cam pulley can be put on backwards and will still work but the dot will be in the wrong place..

Are you sure you're chasing the right mark and that your on #1 TDC compression stroke and not exhaust stroke?
_________________
1980 931S - LSD - FMIC - GTS fuel - hobby
95 M3 manual coupe - summer DD
06 X5 3.0 auto - winter DD
01 RS25 coupe - 90% Retired
06 MDX - bought for mom to DD
81 Rambler BBC 454
97 Tercel long retired/sitting
77 gs750 - 95 300ex - 89 blaster
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Han Solo  



Joined: 11 Jul 2015
Posts: 234
Location: Lebanon TN

PostPosted: Sun Jul 26, 2015 10:12 pm    Post subject: Re: Progress and new parts Reply with quote

Fasteddie313 wrote:

The cam pulley can be put on backwards and will still work but the dot will be in the wrong place..

Are you sure you're chasing the right mark and that your on #1 TDC compression stroke and not exhaust stroke?


I think that's the case with the cam gear. The dot is on the front side. #1 was TDC and the timing mark on the flywheel was in the "window". Nothing moved after changing the belt so I think it's fine.
_________________
-----HAIRY ANT NEST RACING-----
Collecting, racing and restoring Porsches for fun and negative cash flow.
-----Epic 914 race car build----- http://forums.pelicanparts.com/porsche-914-914-6-technical-forum/767721-yet-another-rescue-porsche.html
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Fasteddie313  



Joined: 29 Sep 2013
Posts: 1497
Location: Not Detriot - NMI

PostPosted: Mon Jul 27, 2015 1:30 am    Post subject: Reply with quote

#1 tdc on the oil pump and the flywheel could still be on the exhaust stroke, look at the #1 cyl cam lobes under the oil cap while at TDC, lobes up = compression stroke, lobes down=exhaust stroke(valves open)..

4 stroke engine, every other TDC is compression, cam is geared to the crank 2:1, cam only rotates once every 2 crank revolutions..

Also I think there is a dot on the front and back of the cam pulley for confusion purposes, you want the dot on the back, if the dot on the back is perfect 180 degrees out at #1 TDC you're on the exhaust stroke..

Sounds like a 50/50 chance you're on the exhaust stroke..
_________________
1980 931S - LSD - FMIC - GTS fuel - hobby
95 M3 manual coupe - summer DD
06 X5 3.0 auto - winter DD
01 RS25 coupe - 90% Retired
06 MDX - bought for mom to DD
81 Rambler BBC 454
97 Tercel long retired/sitting
77 gs750 - 95 300ex - 89 blaster
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Fasteddie313  



Joined: 29 Sep 2013
Posts: 1497
Location: Not Detriot - NMI

PostPosted: Mon Jul 27, 2015 1:37 am    Post subject: Re: Progress and new parts Reply with quote

Han Solo wrote:
Nothing moved after changing the belt so I think it's fine.


Make sure, turn the engine by hand first to check for interference just to be safe, if you hit the key and its wrong you need a new head $$$..
_________________
1980 931S - LSD - FMIC - GTS fuel - hobby
95 M3 manual coupe - summer DD
06 X5 3.0 auto - winter DD
01 RS25 coupe - 90% Retired
06 MDX - bought for mom to DD
81 Rambler BBC 454
97 Tercel long retired/sitting
77 gs750 - 95 300ex - 89 blaster
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Han Solo  



Joined: 11 Jul 2015
Posts: 234
Location: Lebanon TN

PostPosted: Mon Jul 27, 2015 1:39 am    Post subject: Reply with quote

Fasteddie313 wrote:
#1 tdc on the oil pump and the flywheel could still be on the exhaust stroke, look at the #1 cyl cam lobes under the oil cap while at TDC, lobes up = compression stroke, lobes down=exhaust stroke(valves open)...


That's a helpful tip. Thanks!
_________________
-----HAIRY ANT NEST RACING-----
Collecting, racing and restoring Porsches for fun and negative cash flow.
-----Epic 914 race car build----- http://forums.pelicanparts.com/porsche-914-914-6-technical-forum/767721-yet-another-rescue-porsche.html
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kcoyle  



Joined: 16 Jan 2011
Posts: 714
Location: Long Island, NY

PostPosted: Mon Jul 27, 2015 3:49 am    Post subject: Reply with quote

Timing mark pictures in this thread if it helps.

http://www.924board.org/viewtopic.php?p=363600&sid=553f1b463e4ef4fa0cea803f4c26d1bd
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1982 931- Stock with MBC at 8psi

Relax, all right? My old man is a television repairman, he's got this ultimate set of tools. I can fix it.
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Han Solo  



Joined: 11 Jul 2015
Posts: 234
Location: Lebanon TN

PostPosted: Mon Jul 27, 2015 9:13 am    Post subject: Rusty tank band aid Reply with quote

Here's what I ended up doing on the leaky fuel tank sump. Two nights ago I spread JB Weld thickly over the lower portion where the pin hole were. Then today after the JB Weld cured, I first trimmed of the drips and then coated the whole sump with fiberglass. That should hold things together until I drop the tank and coat the inside. I finished re-installing the last of the coolant hoses, air filter box and changed the fuel filter after pumping through a few ounces fuel through the open line. That looked clean and I was using a gas can with the fuel line to the external pump dropped in it. Tomorrow I'm getting a new internal pump (ouch $$$) and should have the fuel system completed tomorrow night. Lastly, I cleaned the interior for the second time. Shampooed the carpets, cleaned the vinyl and put the seats back in after paying close attention the the seat rails. Those were pretty corroded and needed wire brushing and heavy PB Blaster application.




_________________
-----HAIRY ANT NEST RACING-----
Collecting, racing and restoring Porsches for fun and negative cash flow.
-----Epic 914 race car build----- http://forums.pelicanparts.com/porsche-914-914-6-technical-forum/767721-yet-another-rescue-porsche.html
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Han Solo  



Joined: 11 Jul 2015
Posts: 234
Location: Lebanon TN

PostPosted: Fri Jul 31, 2015 12:41 am    Post subject: Update Reply with quote

Progress on the fuel delivery last night. I installed the in-tank pump and external pump. Mostly trouble free. You've really got to crank down on banjo fitting though. I did the jumper on the fuel pump circuit to help get pressure and that does help a lot. So with a clean filter, new pumps and somewhat clean tank; I should be getting good fuel delivery (baring CIS and injectors).

I've noted several things during testing though...

The engine seems pretty sluggish when bliping the throttle from idle. Especially when first started. Higher revs after it warms up, it's more responsive. I suppose that could be any several factors including vacuum leaks, clogged injectors, CIS issues.

Also, after the engine reaches operating temp, there's some clatter from the valves or cam shaft. I've ordered a valve cover gasket kit and I plan on getting in to re-torque the bearing caps and adjusting the valves. Are the head bolts accessible to re-torque as well? Any other procedures I should do while in there? Tips greatly appreciated.

Then, unless I find major issues in the cam housing, I'm going to do a compression check. If I find this engine is needing re-build, well that might have to wait awhile.


_________________
-----HAIRY ANT NEST RACING-----
Collecting, racing and restoring Porsches for fun and negative cash flow.
-----Epic 914 race car build----- http://forums.pelicanparts.com/porsche-914-914-6-technical-forum/767721-yet-another-rescue-porsche.html
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ideola  



Joined: 01 Oct 2004
Posts: 15489
Location: Woodstock IL

PostPosted: Fri Jul 31, 2015 1:40 am    Post subject: Reply with quote

I would strongly urge against retorquing the head bolts. Firstly, the head bolts are single use stretch bolts. Secondly, the head gasket is single use as well. Releasing the clamping force on an old engine is only asking for trouble, so unless you're prepared to do a head gasket, I would leave it alone for now. Would be much better to do a leakdown test (rather than a simple compression test) to identify if you have any issues.

It's OK to retorque the cam bearing caps, although in my experience it's not really necessary. Much more important to carefully check all of the valve clearances. I usually go through and set them all to spec on warm engine. Then rotate the came 720 degrees, recheck and adjust, then rotate the cam 720 again and recheck. I've found that rotating the assembly and iteratively rechecking / adjusting is the best way to get the clearances as close to spec as possible. Be sure you don't wind the adjusting screws in too far...you might be in need of replacement / thicker screws.

You should definitely plan to replace the plastic elbow for the cam oiler tube.

Have you checked good lean spark, ignition leads, distributor cap, rotor, and ignition timing? Timing could be off which could contribute to the sluggish revving.

Have you cleaned the AFM? Carb cleaner is effective at removing gummed up / varnished old fuel that accumulates on the AFM mechanisms. Make sure the flapper plate can move freely.

Have you check spray pattern at the injectors? This can help you pinpoint if you're having cylinder-specific combustion issues.
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15 981 GTS | 88 924S SE | 82 931 Holbert | 82 931 Rallye | 81 937 | 81 Euro 931 | 81 Weissach | 80 US 928 | 80 US 931 '941' | 80 US 931 | 80 931 GTR | 79 Sebring | 78 D-Prod Replica | 78 w/D-Prod kit | 78 Poli-Form | 78 Limited Edition | 77 Martini
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Han Solo  



Joined: 11 Jul 2015
Posts: 234
Location: Lebanon TN

PostPosted: Fri Jul 31, 2015 3:48 am    Post subject: Reply with quote

ideola wrote:
I would strongly urge against retorquing the head bolts. Firstly, the head bolts are single use stretch bolts. Secondly, the head gasket is single use as well. Releasing the clamping force on an old engine is only asking for trouble, so unless you're prepared to do a head gasket, I would leave it alone for now. Would be much better to do a leakdown test (rather than a simple compression test) to identify if you have any issues.

It's OK to retorque the cam bearing caps, although in my experience it's not really necessary. Much more important to carefully check all of the valve clearances. I usually go through and set them all to spec on warm engine. Then rotate the came 720 degrees, recheck and adjust, then rotate the cam 720 again and recheck. I've found that rotating the assembly and iteratively rechecking / adjusting is the best way to get the clearances as close to spec as possible. Be sure you don't wind the adjusting screws in too far...you might be in need of replacement / thicker screws.

You should definitely plan to replace the plastic elbow for the cam oiler tube.

Have you checked good lean spark, ignition leads, distributor cap, rotor, and ignition timing? Timing could be off which could contribute to the sluggish revving.

Have you cleaned the AFM? Carb cleaner is effective at removing gummed up / varnished old fuel that accumulates on the AFM mechanisms. Make sure the flapper plate can move freely.

Have you check spray pattern at the injectors? This can help you pinpoint if you're having cylinder-specific combustion issues.


Just the advice I was looking for

The valve adjustments will definitely be done and thanks for the heads up on the elbow.

I did replace the plug wires, plugs, rotor and distributor cap but have not checked timing with a light. That needs to be done also.

The AFM should be clean as I've sprayed a can of Sea Foam through the intake.

I've used Witch Hunter for injector cleaning on two other Porsches and found their services do wonders for old injectors. These will be taking a trip there at some point.

Meanwhile I've got other fixes on the list like bleeding brakes, replacing master, slave and clutch hose. I best slow down a bit or I'll run out of things to tinker on this fall
_________________
-----HAIRY ANT NEST RACING-----
Collecting, racing and restoring Porsches for fun and negative cash flow.
-----Epic 914 race car build----- http://forums.pelicanparts.com/porsche-914-914-6-technical-forum/767721-yet-another-rescue-porsche.html
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ideola  



Joined: 01 Oct 2004
Posts: 15489
Location: Woodstock IL

PostPosted: Fri Jul 31, 2015 4:04 am    Post subject: Reply with quote

I've used Witch Hunter on several sets of 931 injectors. However, the last time I tried to send them some, they said they were no longer doing the CIS stuff. I was getting about a 60% failure rate where injectors simply could not be made to flow evenly or consistently, even after multiple iterations of cleaning. FYI.

SpecialTAuto still advertises CIS injector cleaning, so they might be another resource in case you meet with the same results I did with WH.

I've not used SeaFoam before, so I can't comment as to its efficacy. I would recommend checking the AFM plate movement by hand to ensure it's moving freely.
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15 981 GTS | 88 924S SE | 82 931 Holbert | 82 931 Rallye | 81 937 | 81 Euro 931 | 81 Weissach | 80 US 928 | 80 US 931 '941' | 80 US 931 | 80 931 GTR | 79 Sebring | 78 D-Prod Replica | 78 w/D-Prod kit | 78 Poli-Form | 78 Limited Edition | 77 Martini
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