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Cheap 88: Front engine job

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Old 10-02-2017, 11:05 AM
  #16
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Originally Posted by AirtekHVAC View Post
Nice. Post pics of the exhaust patch!
Can't. I had to use the gas welder, and the exhaust was well oxidized, also my welding technique with the gas welder isn't very good. I'm ashamed that it's not a beautiful bead. It's strong but kinda ugly. Not sure what to do about the heat shield, but I think I'm going with some light stainless and steel rivets. About the best I can hope for with that.

I'll be starting assembly later today, once I get a main seal, and some other gewgaws from Roger. So far aside from the exhaust pipe the rest of the job is nominal. Very little oil leaks, and none from the oil pump housing.
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Old 10-02-2017, 11:51 AM
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Roger probably has a heat shield over there. Just replace it. It will save you a lot of time jacking with it.
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Old 10-02-2017, 09:07 PM
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Originally Posted by soontobered84 View Post
Roger probably has a heat shield over there. Just replace it. It will save you a lot of time jacking with it.
They are spot welded on. I'm gonna put a rivet patch on it.

Made good progress today. Front is cleaned(enough), drained the black, and pulled the alternator, got the WP and tensioner sorted and installed. Waiting parts for now.
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Old 10-03-2017, 01:04 AM
  #19
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Oh I see now. The heat shield that is a part of the catalytic convertor is sawed through. I thought it was the heat shield that is mounted above the exhaust to the underside of the body.
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Old 10-08-2017, 02:25 PM
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Brief update, had a profitable morning. New crank seal, new cam gear on. Got the belt on, and tensioned, got the covers on except the right side. worked underneath for a while, and got the front exh on, and the back exh off so I can repl the rear pinch bolt. Found another 7000 mud daubers. started on the injector removal but waiting for cleaning before pulling them out of the holes. Taking a break for some yard work, but I think it'll drive again in a few days, depending on work pressure. Nice weather so I'm spending more time outside on Sunday as I boycott NFL.
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Old 10-08-2017, 06:26 PM
  #21
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Drained my diff, and REFILLED. Confirmed I have LSD - yessssss.

pulled out the T-stat and the bottom seal was toast. Ordering a 174F thermo, which is a few deg cooler than stock. Doing the front brakes later today, and rear rotors being turned now. Having the alt tested before install then I can close up the front of the engine, and put it back on the ground.

Now that I have the calipers off, I'll clean them well and paint red.

Making great progress not watching football.
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Old 10-10-2017, 09:29 AM
  #22
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Originally Posted by docmirror View Post
Tell us more. Wacha got, wacha got, wacha got?
This...







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Old 10-11-2017, 11:40 PM
  #23
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OK, both pinch bolts done, and torqued to something like 840 Newts. Ah dohn know. Oil and filter done, brakes all done, and once I get the AC belt and the Alt belt on I can put it back on it's feet. Will do the trans filter and fluid on the rack at Rog house. I HATE working under the car. Took off some fuel hoses, and looking into that now. Will be swapping out the inj once I get it back down.

Don't tell anyone, it's a secret - but I MAY make it to 3rd coast in this car. Possibly. Won't be painted, or int sorted, but if it runs, and stops I might risk it.

Brakes before and after. Wondering if I can get the 'Porsche' script painted by hand if it will look good? I'm not that **** but it would be nice to have a contrast.
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Old 10-11-2017, 11:51 PM
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Just take an abrasive block and block-sand the Porsche script down to bare aluminum. Then sponge paint it white, or leave it 'natural'.
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Old 10-12-2017, 12:57 PM
  #25
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Great progress Doc!
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Old 10-12-2017, 02:19 PM
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Love the repainted caliper picture. For those playing along at home, note that Doc has avoided painting the bleeder screws and the crosspipe. The original calipers have the bleeders and crosspipes installed after painting, so are yellow cad and natural cunifer color respectively. The crosspipe turns a dark brown almost-black color naturally. You can use a little copper polish on it to restore the original new color to it and then clear-coat it. Note that there's a bit of protective black tubing on there originally too, in a short bit of the middle section where it passes through the ears on the caliper. Vacuum tubing would be a logical choice for that except there's no good way to get it over the nuts on the ends after the line is flared. You can split a piece of vacuum tubing and glue it on to match the original. Black glossy heat-shrink may be the next-best option for that, but in my experience it needs to be replaced every few years thanks to the heat from the nearby brakes.

Kudos to Doc for getting these details right!

The through-bolts that hold the caliper together were originally yellow cad, installed after the castings were painted. The factory recommendation is that you don't remove them, and I can tell you that it takes a bunch of heat to loosen the threadlocker that Brembo used during original assembly if you do decide to pull those bolts out. Appearance-wise, it leaves the exposed bottom end of the bolts yellow cad against the color of the casting. In a refinish effort, that means the bolts need to be out for the painting, then the bolt screws up the painting in the outer ends of the threaded holes as you put them back in. Unless done perfectly and touched up precisely after reassembly, it will always look "funny". Best to do as Doc has done and paint the bolts in place unless you are really **** about this detail.

The later (86.5+) caliper castings were anodized black, then it looks like they had a bit of clearcoat added after that. At least that's the way mine were prep'd. I was able to water-blast the clearcoat layer off without damaging the black anodizing any more than it was already, and refinish as original with satin clearcoat. They don't have nearly the same striking visuals as Doc's reds do. You can easily see in Doc's "before" picture where the clearcoat has failed, exposing the raw satin anodized layer underneath.
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Old 10-12-2017, 03:55 PM
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Thanks, I was pretty careful, but yes - left the bolts in. However, I did take the time on the inside to tape the cross bolt heads so they remain unpainted. After that, with a dental tool and a small exacto, one can go back and clean off any overspray on the bolt heads back there.

Ideally, I should have taken off the cross pipe, and also remove the nipples. I actually taped them, and went back with some scotchbright after the painting to touch up. I think I'm going to drive it a bit, and then go back and do the refurb of the hyd system next, with new flex hoses, and clean out the cups and new cup seals. Hoping like most dual piston designs, I can get the cups out without splitting the housing. I avoid splitting the housing, but I can if needed.

I may not worry about 30YO cooling hoses, but I worry a fair amount about 30YO brake lines. eeeeekkkk!!!

Work continues apace. Today is the alt(tested good at Oreilly's), AC belts, and then the cross wires to right fender, ign wires, and it should come down on it's new feet(bought new wheels, picking up Friday) early next week. I'm excited to finally put a few miles on it and see if it's a decent driver.
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Old 10-12-2017, 05:28 PM
  #28
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Originally Posted by docmirror View Post

pulled out the T-stat and the bottom seal was toast. Ordering a 174F thermo, which is a few deg cooler than stock. .
Doc,

79C is an unusual temperature setting for a 928 thermostat - I have used the 75C unit.

No idea if you have a strong reason for using such but the 75C unit I had got binned some time ago- figured it did nothing for the motor and that Porsche did know what they were doing when specifying the stock item at 83C.
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Old 10-12-2017, 05:40 PM
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Originally Posted by FredR View Post
Doc,

79C is an unusual temperature setting for a 928 thermostat - I have used the 75C unit.

No idea if you have a strong reason for using such but the 75C unit I had got binned some time ago- figured it did nothing for the motor and that Porsche did know what they were doing when specifying the stock item at 83C.
There's sort of a method to my madness. Each engine management system is configured differently, and the maps for the fuel and ign are in some cases closely dependent on the running temp of the engine. I have no inside knowledge of the fuel/ign maps for the S4, except that I know there is obvious enrichment for cold start, and warm-up.

So, I'm hoping that the slightly lower, but not too low temp will be within range of the fuel maps to give the proper stoich ratio when operating warm, and also give me a bit more margin during hot days. Having said such, I realize once the T-stat is fully open, and the system is in full exchange, the size of the orifice of the T-stat is what determines the flow, and not the actual temp set.

The 928 has little reserve cooling capacity after it's long life, and various old systems being in play. I have a rebuilt rad, new water pump, cleaned and drained the block, new slightly lower temp T-stat, fully functioning fans, and fan controller. Basically, I'm giving it every opportunity(plus a little help) to maintain an even temp in the worst cases.

On my 911, in summer after I bought it, I replaced the WP, low temp T-stat, cleaned the rads and evaps carefully, and also added a center radiator. It was absolutely fantastic the difference in running temps from bone stock. Lower running temp in 105F days, better oil pressure, slightly better fuel econ, and even the AC worked better. The 911 folks swear by low temp operations, and I am moving that same philosophy over to the 928. Of course, they are very different platforms, but when I did similar things on my 92 968, the results were also quite good. Hoping for the best outcome, as I had it all apart anyway.
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Old 10-12-2017, 08:22 PM
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I ran a lower-temp thermostat in mine for a long time. It did run cooler while the thermostat was in control, but the fan controller would still let it go back up to "design" temp range once the thermostat was out of available range. For some yet-unexplained reason, the fans run less now with a new normal-temp thermostat installed. Nothing else was changed, making this an interesting conundrum. I'm not complaining since it again works as designed -- just no good explanation of why the fans were running so oddly with the 75║G 'stat. The dash gauge needle is pretty rock-steady at two needle-widths below the 190║F mark regardless of load now, plus it warms up faster now. Contrats with the 75║C performance, with the needle settling cool a couple needle-widths above the 170║F mark but drifting up to where it sits now when pressed in 100║+ ambients and full AC load. You comment about the size of the thermostat opening may have a part in all this too.

It's in the high 20's overnight already, so heater performance is now most important. It's snowing at the ski area already, but not enough yet to open for the winter. Yet. I have set of ski racks for the 928, but they will never get used on it here. Too easy to throw everything in the Pilot for the dash over to the lodge, and not worry about de-icer and cinders on the road and the aluminum underpinnings supporting the 928.
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