924Board.org

[jacobroufa]

Drove it a bunch today and I was paying closer attention to the vacuum/boost gauge. I was seeing 7-8 in/hg at idle and no more than 3-4 psi on boost. Fuel filter and injector cleaning definitely helped a lot, but still not where I knew it could be. Well I should have been paying attention to that gauge more closely for the last couple weeks but I have a lot of little things nagging at me. Anyhow.

I remembered how much the vacuum lines made a difference in how the car ran when I did them back in 2020. I thought to myself "no way they could be rotted already", but figured it was a quick thing to check. Pulled off the line from the throttle body as it is easiest to get to. Sure enough. Dry, cracked, perished. Ugh.

Well, I was going to dig into the turn signal stalk, to see if I could get the twitchy high beam resolved, but I guess this problem stared me closer in the face. I remembered that I had enough line left from last time, sitting in sealed bags on the shelf. Changing all that out is more of a pain than I wish it were, but oh well.

17-18 in/hg at idle
7-8 psi on boost

Idles a lot more smoothly, and stable at a lower RPM. I don't smell fuel as aggressively, so has it leaned out the mixture as well because it doesn't have to compensate for all the leaks..? I'm happy, that was time well spent. And when I do it again, it'll be silicone lines.

Guess the electrical gremlins will wait until next time.
_________________
1980 Porsche 931
1981 Porsche 924 Weissach

[Cedric]

Mixing two archaic measurements at the same time, my metric mind is bent Im glad it runs better, dont you have any wideband to put in for some measurments, that would take some guessing of the fuelling. And it should be possible to run euro boost safely. Some day i might buy a smoke tester for finding small leaks in intake and vac system, would make life easier

The dash lights leaves some to be desired for sure, especially with the green on black, I cant see anything when its dark outside, not optimal..

Mine feels very stable at 100mph/160km/h, or more, but its many parameters that affects that.
_________________
1980 924 Turbo
www.instagram.com/garagecedric/

[jacobroufa]

Ahaha! Sorry. That is what my gauge reads.

I have a wideband sensor on the shelf, that will be another installation very soon as well! This sensor has its own gauge and readout, purely for measurement. How do I ensure it functions as the existing O2 sensor which I would remove? I know it can send data as well as display..

My plan is to buy Ciprian's EFI kit towards the end of summer and with that I will be able to hook up the wideband to that ECU, so it will be more effective.

For now though, what should I do? I will see what I can read into how it works, from the shop manual.. Maybe there is more outdated junk I can just remove.
_________________
1980 Porsche 931
1981 Porsche 924 Weissach

[924RACR]

What brand do you have? It's usually possible to set up the output to mimic a stock style narrow band O2 sensor, which you could wire into the stock Lambda ECU while watching the gauge for function... and then wire to the MAXXECU later for the conversion, reconfiguring the gauge to send out the linear wideband output.

I use INNOVATE WBO2 sensors these days on my cars, and they actually have two analog outputs...
_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

[jacobroufa]

Yep it's an Innovate kit... PSB-1. Glad I got it a couple years ago knowing I'd eventually use it.. they have gone up $100 in two years!

Looking at the manual:

[924RACR]

Yeah, that's exactly the same as my MTX-L gauge setup...

Don't forget to cal the sensor as you install, before you screw it into the pipe!!
_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

[jacobroufa]

Well so this is fun. I drove it a bunch yesterday. Didn't look under the hood after I got back -- usually have done so this last month and change as I've gotten it back up and running -- and today popped the hood and found my coolant tank completely empty.

So I've had this little problem, after a drive the tank will lose 1-2cm of coolant, so I have had to keep it topped up. It's not leaking anywhere that I can tell. Seems to be overpressurizing and coming out the cap. Cap and bottle are both brand new.

Based on what I've read, this can be a sign of a head gasket failure, one failure mode where the coolant and oil do not mix.. I've just been keeping an eye on it, topping up as necessary. Car has not overheated, it's been in good temp ranges.

Well, I spoke with a couple board members Mike and Ciprian and they're saying probably I should just pull the head and take care of it. Definitely don't want it to get worse.

I was planning to pull the engine and reseal stuff, take care of oil leaks and such, over this winter. I had hoped to be able to drive the thing throughout the season. Now it seems my hand is forced.

---

So new plan. Get the EFI kit a couple months early, pull engine and reseal now, and hope to get it done before summer's fully out.

I'm putting together a parts list (thanks to the PET) but I'm definitely wondering for anyone's input here on what I should take care of while I'm in there? I'll put a link to the spreadsheet when I've finished.

Some of the "while I'm in there" stuff that I'm thinking:
clutch, master/slave cylinders, engine mounts, battery terminals, ground straps and main battery/starter/alternator heavy gauge wires...

I may go so far as to set up a FMIC, as I have a turbo compressor housing from an Audi that I got from Eddie several years back. This was the housing that he used on his S1 before he upgraded, and let him clock it to face down and run an FMIC. I think I also have a billet compressor wheel stocked away somewhere; if so that might be a nice upgrade also.

I'm sort of tempted to contact Catellus Engineering who do G31 rebuilds, and see what it would cost to take care of my 1/2 synchro and maybe put an LSD in it. Thought being if I am going through this trouble and the engine will be out for a month or two while I work through it, I might as well go the extra mile..

---

I dunno. My head is kind of reeling right now. I don't want to go too overboard, but my hand is being forced, so maybe now is the time..


Any advice, thoughts?
_________________
1980 Porsche 931
1981 Porsche 924 Weissach

[jacobroufa]

Parts list: https://docs.google.com/spreadsheets/d/1R_L4_zrrBnVGEAdaLG69KRs-kAwh9VnpBJLbx4vQOwI/edit?usp=sharing

Questions:

1) What exactly is included in the Reinz head gasket set? That could save me ~$50, maybe more? I am unsure but this is my best guess based on pictures I could find. Might reach out to the manufacturer and ask. Worth it at this total cost?

2) What to do about NLA items?
- Exhaust manifold studs (M8 x 25) -- unsure if I need this, but based on what I see others have gone through it seems like a good idea
- Oil filter pressure spring seal (42x49) -- if this is rubber, guessing it is perished
- Manifold to J-pipe nuts (M10) -- can I use another M10 nut as found on the list (turbo to exhaust pipe)?

3) Anything I'm missing or should do differently?
_________________
1980 Porsche 931
1981 Porsche 924 Weissach

[peterld]

Reinz gasket set is fine, unless you are going to use a Cometic MLS head gasket. Then you'll need both.....buying all the rest of the gaskets separately is outrageously expensive.
Studs of any length...try Summit Racing. Bought a pack of 50 cheaper than buying 8 from Porsche. Or try any of the bolt/fastener places you guys in the States have.
Rubber seal...if it's not leaking now then it probably can be reused, just make sure it's replaced in exactly the same orientation.
Porsche manifold nuts are extremely soft...just about one use only. With top quality tools (German) and correct fitment the nuts just want to round out the corners. Brass nuts are good, but again try any of the race shops/fastener places.
Rather than pay the Porsche tax, it is worth doing an internet search for the part numbers. I've found other members of the VWG have considerably better prices.....think Skoda or SEAT.
_________________
80/81 932/8 ROW

[924RACR]

Not that pulling and doing a rebuild isn't a good idea, but... did you pressure-test the system yet? Should probably do that before you commit; at very least, you might have some smaller loss point and could fix and enjoy the car more this summer, then do a full rebuild off-season.

Better yet, drop the EFI kit on now and REALLY enjoy the car for the summer, then easier to get back on the road (thanks to the reliability of the EFI system) in the spring.

Not saying they're wrong about the HG failure possibility - but why guess when you can have solid answers?

Now might be a good time to consider doing the ARP head studs - remember they're Ford Cosworth, fairly cheap from Summit. Even with stock boost and headgasket.

I do agree the Reinz set is perfect, all you need.

All the exhaust nuts should be replaced with new copper locking style, reduced head, readily available from Bel-Metric. Including those J pipe ones.

Exhaust manifold etc studs - if you need them, search around on the board, there are probably some good sources from Volvo turbos I think we've heard... need to chase part #'s, but they'll handle the turbo heat better than generic replacements.

Realize you may be in for broken rings, possibly even needing pistons; just be open to the possibility, you won't know till you get them out.

You might consider new valve springs; now available from Porsche. Of course lap the valves in to ensure sealing (in addition to cleaning them).

Clutch is a definite no-brainer. Mounts are a good idea too, clutch hydraulics OK sure though doing them while all is installed doesn't make any difference.

Now is definitely the time to do any turbo work, since it'll be much harder to swap the turbo with the motor in the car.

New water pump, t-stat, and belts of course, if it weren't obvious.

Make sure your exhaust manifold isn't cracked, and weld up or replace if so...

Would be worth having the rad cleaned/checked, if you haven't recently, since it'll be out.

Pull that breather out, soak in gas, and shake/bang all the old accumulations out.

Since the front end is disassembled, could be a good time to recondition the a-arms (clean, repaint, new bushings) and new strut mounts too, if not recently done. Might as well have a car that drives well, after all that work.
_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

[jacobroufa]

Sounds good on the Reinz set. It looked as it did not have all the turbo related gaskets in there so I wanted to be sure.

Thanks for the notes on the studs & nuts.

I planned to pressure test the system this evening.. I will post back results on that.

Getting the EFI kit now regardless!

I can't believe I forgot head studs on the list!

I did a compression test yesterday as well: 120, 116, 124, 126. Cylinder 2 is a little low compared to the rest but not fully out of spec. Unless those numbers are all lower than should be? Even as such that could mean new piston rings?

I have clutch cylinders on the shelf as a planned todo, that's why it was mentioned. Dan did not know when they were last done, when I bought the car from him in 2019. Just figured while it's out it is simpler.

Thanks for the note on the breather.

A arms, bushings, and strut mounts all were done very recently. Doing struts though, while I wait for parts.
_________________
1980 Porsche 931
1981 Porsche 924 Weissach

[924RACR]

Yeah, I DEFINITELY see Turbo-only gaskets in that set - like the turbo manifold flange, and the charge tube gasket. So if the picture is accurate, it's definitely the right one. Certainly doesn't look like an NA set.

Compression numbers look reasonable.

I wouldn't have the thing open and not throw in new rings and a quick run of the ball hone across the cylinders, de-glaze.

You were at least planning new rod bearings, right? May or may not need new mains, have to see how they are (but those are much harder to find).
_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

[jacobroufa]

Sounds good, thanks Vaughan. I guess rings are on the list now!

Looking at other posts you have made about rings you use Total Seal? Do you have a part number by chance? Or should I wait until I have everything apart to measure the bore?

I don't know what to plan truthfully, so rod/main bearings were not necessarily on the list either.

Every other car I've done a head gasket for has been a bare necessities job. On this one, I figure it's worth doing as completely as possible as I'd like to not have the engine open again any time soon.

I guess for this I figured the bottom end was good aside from wanting to do front/rear main seals while it's out. But happy to take a recommendation to go further if you think it's a good idea. I'm out of my depth at this point.
_________________
1980 Porsche 931
1981 Porsche 924 Weissach