85 911 Questions

[85911]

My wife totally surprised me with this car and although I have worked on cars for many years, never a Porsche. I have a lot of questions. It has under 65,000 miles and runs well. The oil pressure is around 3.5-4 bar at temperature. The only issues are a slight surging under load, and an odd shifting feel between 1 & 2 and 2 & 3 (the PO had the rear shifter bushings replaced just before I got the car).

So far, I have replaced the front condenser motor and the fresh air blower motor, disassembled the evaporator blower housing and lubricated the motor, will lubricate the 3 heater blower motors, had the evaporator cleaned & checked for leaks(there were none), will soon replace the expansion valve (Egelhof), receiver dryer (Kuhl), and install new barrier hoses (Kuehl). (I have enjoyed following the "My AC burns me up" post and have done and will do many of the same items.)

Next steps are: change oil (Valvoline 10W-40)(the "S" hose is good), with filter (K&N HP 4004 or Mahle-Knecht OP 54), adjust valves (0.004 in. cold) w/ new valve cover gaskets and nuts, perform compression test, flush/replace brake fluid (DOT 3), replace transmission oil(SAE 90 Hypoid Gear Oil: GL-5), replace front rotors (currently @ 0.875 and 0.878 and they need turned)(Zimmerman), replace fuel filter, and it will soon need rear brake pads (Textar).

I will replace the spark plugs when I do the compression test, but my local parts store didn't have either Bosch WR7DC (copper) or WR7DP (platinum). I could order them. Should I stick with the original plug specification or does anyone have a recommendation for a good substitute?

Longer term, I will install the recommended (by the Pelican Forum members) fuse links to protect the electrical system. And, I will probably be looking for upgrades for more HP but for now, I think that's another post.

If anyone thinks I'm missing something or using the wrong parts/fluids/supplies above I would appreciate it. Thanks.

[tdw28210]

CHeck that oil weight..pretty sure 95% of the guys here would say to run 20W50 - unless you are way up north. As for brand: Brad Penn, Kendall or VR-1 seems to win most debates.

[gliding_serpent]

awesome wife!

[85911]

tdw: Thanks for the reply. Your oil weight suggestion makes sense. It's an old car and air cooled. I'm in St. Louis and it hardly ever gets cold here anymore.

I just bought NGK BPR6EGP 7084 plugs which is a platinum plug. For this car, Bosch now calls for a 7900 plug which is copper. Apparently it no longer makes the WR7DC or WR7DP. I will assume the NGK is ok unless I hear otherwise.

Thanks again.

[DRACO A5OG]

Oh my does she have a sister :-D

Welcome aboard brother.

Oh no please use standard copper plugs NGK or Bosch.

[85911]

Why is copper better than platinum, or irridium? They claim the exotic metals lower the spark voltage and wear more slowly.

[gamin]

Looks exactly like my son's 85. He drives it every day. We use 20w50 Valvoline VR-1 racing oil non synthetic. Also use NGK plugs. You don't need to pay fancy money for fancy plugs.

[javadog]

I would use;

Brad Penn or Swepco oil.
The original Bosch plugs, which can still be found, or NGK BPR6ES plugs.
Filters, brake rotors and pads sourced from a Porsche dealer.
Kendall trans oil.

I'd probably change the fan belt, also. You should also adjust the clutch. Don't just adjust the free play in the release mechanism; set the preload and travel on the cable, too.

While the rotors are off the front, check and adjust the front wheel bearings.

You might also change the brake fluid, adjust the parking brake, etc.

FWIW, I buy zero, nada, zip from my local parts store...

JR

[TheSt|G]

Are you saying that your are idling at 3-4 bar of oil pressure? If so, sounds like it is overfilled.

[CCM911]

I buy the Bosch "plain-jane" plugs from either Pelican or FLAPS. Very cheap, and work just fine. I forget the code. I think it is something like WR...

[85911]

All: Thanks for the input. Looks like I'll take back the NGK "GP" for the "S" (although I would like to know why- the plugs I put in my newer cars run well and last a long, add clutch and front bearing pre load adjustments, and a new fan belt. Good suggestions.

No, the oil pressure I mentioned is at cruising speed. At idle, it's around 1-2 bar.

Again, thanks for the help.

[RD911T]

Welcome! I'm in Cape Girardeau, but grew up in StL.

Nice car, awesome wife. You're getting great advice on the oil here.

[Nick Triesch]

Just use the tune up kit our host sells. Works fine.

[scarceller]

I use these plugs:
NGK BPR7EIX (4055) Iridium plugs
The iridium plug simply keeps it's gap set for longer time than the standard plugs.
I also increase the gap slightly from stock spec of .8mm I gap them at 1mm as it helps with idle mis-fires in engines running the O2 sensors closed-loop.

But the plugs you bought NGK BPR6EGP 7084 are also just fine and 1 level hotter than the stock 7 plug.

The surging issue should be investigated, I'd start by have base mixture checked and making sure you don't have any vacuum air leaks in the intake, usually broken vacuum lines.

[Dave Colangelo]

Great looking car!

I use Mobil1 but lets not get into that debate here...

First off I would tend to everything else before touching the AC in these cars. You have a Targa top, that is better than any AC unit will ever be. The AC is notoriously bad in these cars and the best solution is to replace it with a modern system as Im sure you have read in other threads.

As for general work when ever I get a new Porsche or every year I do, fuel filter, air filter, plugs, oil change, distro cap and rotor, and in my 911 the fan belt. This is my "general maintenance" and goes a long way to keeping my cars running well.

Take a look at your plug wires they get old and dry out fast.

Another point of advice is to ALWAYS CARY A SPARE DME RELAY (or jumper). The DME relay controls power to the ECU and fuel pump. They are notoriously problematic in Porsches from this era and not all that expensive. Its worth it to have a spare one on you so as not to get stranded. Spare fuses, electrical tape, wire and a few other odds and ends have saved me in the past as well. I also keep a fan belt and washers in the car. Remember to keep all the tools you need to replace the parts as well since spare parts are on good if you cant use them.


The most important think to make sure when you change the oil
DONT FORGET TO DRAIN THE OIL TANK
Most car guys are used to draining the oil from the one bolt on the bottom of the engine casing. While the 911 has this bolt (and a bit of oil will come out) the majority of the oil is in the oil tank since its a dry sump system. There is a second plug on the passenger side rear for that tank. Many first timers dont realize this, open the sump bolt, see almost no oil come out, get very very nervous. Put 10 quarts back in on top of whats in the tank and now have close to 20 quarts of oil in the car, Not Good! I did this the first time I changed the oil on my 911...

Regards
Dave

[86 ssinit]

Nice car great color!! Your getting great advice above good luck with it. One thing you may want to check is the oil pressure 1-2 at idle seems very low even 3-4 at load seems low. Maybe gauge is off but I would check that out. These guys know a lot more than me and I'm sure someone will join in with more info.

[Flat Six]

Nice; welcome! Great wife, BTW.

+1 w/Sal re: vacuum leak for your surging issue; check O2 sensor as well. Though doesn't affect performance under load, you'd be wise to check & clean ICV, too.

In addition to what you've already mentioned, I'd put headlight relays at/near the top of your list as well. Get yourself some spares, like extra DME relay, fan & AC belts, ceramic fuses, fan pulley washers (even if you have all six now, get a couple extra in case you crush one or two replacing your belts). Get a replacement rod end for your autoheat control box; if it hasn't broken yet, it will. Cheap to get now & add to your PP order without 'single item' shipping.

*** Make sure you un-freeze the trans fill plug before you remove the trans drain plug. ***

For the 915 I prefer Kendall NS-MP myself.

Re: shifting, you should probably check the ball cup bushing at the end of the shift handle and the shift rod bushing in the tunnel, too. Good time to R&R and re-lube. And as long as you're in there (wink) you're most of the way toward installing a Seine shifter kit . . .

You also might want to secure your cruise control cable to the heater duct in the engine bay. Should be a small white plastic omega-shaped clip that pops into a hole in the duct. Leaving it loose as it currently is you'll put a lot of stress on the black plastic adjusting nut, which will inevitably break and create a potentially dangerous throttle condition.

[tdw28210]

I use Mobil1

To the dungeon!!! and commence with heating up the vat of boiling water!!!!

[Dave Colangelo]

Originally Posted by tdw28210

To the dungeon!!! and commence with heating up the vat of boiling water!!!!

Hahah not to open up a can of worms, but I have never had an issue with it, never had a leak or a strange engine noise. I would like to move to Brad Penn but the car is not really where I want it to be yet. So until I tend to some other thing I wont spend top dollar on oil.

Regards
Dave

[TheSt|G]

-Check various rubber seals
-Reinforce the door stays to keep them from ripping through the door skin
-Use Wurth HHS-K on all hinges/metal on metal moving parts
-Headlight relay
-Check drains for flow(sunroof, gas cap, etc)
-Check seatbelt integrity
-Check engine sound pad
-Check bushings
-Check shocks
-Fuel filter
-Check oil lines during change
-Gummi Pflege on gaskets
-Spare key?
-New drain plugs
-Replace missing toolkit tools
-Check gas cap cable
-Replace door vapor barriers
-Spare door clips
-Case of Kroil

Just things of the top of my head I've hit recently and haven't been mentioned already.