March 2024 - Dump pipe

After a lengthy roadtrip in January, I noticed there was a very obvious exhaust leak that sounded like it was near my feet. I pretty much knew straight away what it was going to be caused by - the gearbox mount I’d made that secured the dump to the gearbox bellhousing.

Ever since doing that I’d read how it should’ve been done instead, i.e. with something that has a bit of give in it to allow for expansion/vibration/contraction. I had other priorities on the car as it was working, but now it was broken, I wondered what I should do? Patch it up and bung it back in? Take the car off the road for a bit, get it sorted and then be done with it for longer? I went with the latter, and it was off the road for probably 8 weeks total while I sorted that and some other stuff out.

I decided after a great amount of difficulty removing the flange bolts that I’d make v-band adapter to make it easier to service in future, as I had a leftover 3” aliexpress v-band from the last exhaust adventures. I got new locknuts and a couple of studs that got munted for the flange, too.

I asked around some places and ended up picking up two mandrel 90’s and a 45-degree bend in 3" from Pacemaker exhausts, who made it up to order, and when picking up I got to walk around their warehouse.. properly oldschool cool workshop - and huge. Nice to check out some local manufacturing.

With the bits in hand, I set off fabbing up the new dump, only keeping the turbo flange from the original dump. I used this as an excuse to get a small desktop belt sander to help me get the pipes matching up, and it was a huge help.

The turbine flange was really thick, so I welded that side from inside well, and die grinded it down, as well as from the outside once I'd cleaned up the surface.

I am not a professional welder, and my mates suggested a tshirt saying ‘a grinder and paint make me the welder I ain’t'. I lol’d.

As I got through it, I figured if I’m gonna make it nice, perhaps I should have it coated. I hate exhaust wrap, and figured it might be a good option. Pacemaker offer it as a service as well, and for $180 I decided to give it a go. It’s blasted and ceramic coated with a matte black finish inside and out, and came out looking pretty decent. They do a chrome coating finish for extra, but their most durable finish is the matte black so they say, and it's also the cheaper option. I have no need for bling on this, but the headers they make with that finish would look amazing on a shiny engine bay.

Got it installed and I’m happy with the result. One other thing I fixed up but didn't take photos of was the coolant hard line to the oil cooler that had been leaking for a while, so removed it, resealed the block and fitting and it's now no longer leaking. Huzzah. Was heaps easier to do without the dump in the way.

ramrod

Good shout - I did pull it off and inspect it as I was almost going to replace it, since the ones on the manifold are straight, don't have barbs and using silicon hose makes it hard to clamp the hose to without going nuts on the hoseclamp. Everything seemed clear there I think, but maybe I'll just double check in case I glossed over it.

@Major Ledfoot - Give me a yell if you ever want to part with one of those I'd thought about going with the 'more proper' solution once I found this issue, but figured a free solution I had on hand would do for now. Ultimately I'd like a better, more easily serviceable PCV system like that, with a decent catch can.

July 2024 - Fuel pump

I backed out of our driveway one day and thought I’d stalled the car from not giving it enough revs, but then the car didn’t want to start back up. I could hear the main fuel pump running so figured it might be spark or ECU or something else..

I was stuck diagonally across my road, and with the help of a neighbour and the starter motor, I got it off the road and back into the driveway.

I tested injector firing to rule out CPS, ECU and injectors and tested a timing light on the spark leads, so my eyes turned to the fuel system.

I'd read on a turbobricks thread that a failing lift pump can sometimes cause this issue, particularly when it's just under half a tank (which it was) so started looking at that.

I tested the fuel pumps individually and both seemed to be working from what I could hear, and with no further diagnosis I consulted fellow 940 enthusiast @nugget_940 for advice after coming across his thread on the topic.

After some rather exuberant spreadsheeting in collaboration with him regarding parts required, I fired up the parts cannon and taking advantage of EOFY sales, got some shiny new parts for the fuel system, specifically:

• Raceworks EFP-500 340lph E85-compat fuel pump

• New E85 compatble hoses (5/16” and 1/2”) - (HPH-080-05M, RWH-400-08-1M)

• New stock Ryco fuel filter (Z311)

• Wiring bulkheads (FSA-499)

• Fuel-safe heatshrink, wiring and fuel hose (FSA-095)

• Fittings for fuel filter (RWF-731-06BK, RWF-732-08BK)

• Barbs for fuel filter fittings (RWF-402-08BK, RWF-412-06-05BK)

• Submersible 8mm hose - (Dayco 80160)

With everything in hand, I started pulling the old stuff out and got a bit of a surprise.

The in-tank fuel pump was replaced with a high-pressure unit at some point, likely when the previous owner turbo’d the car on the old engine before that was ripped out and the shell was sold to me. I was under the impression it was stock, and I put a high-pressure unit under the car. Turns out that’s probably been unnecessary the whole time, but meh. In-tank fuel hose was marked as 1995.

Though the pump was upgraded to a high pressure unit, the 11mm fuel hose coming out of the tank was not rated for high-pressure, but was the original 0.05mpa (i.e. ~7psi) hose originally on the car. It was marked as 1993, so original, and was cracked at the ends. I’m pretty glad it didn’t burst and set things on fire.

The old pump was removed from the hanger, and the Raceworks pump was installed, securing it with hose clamps in the original position. I tried using the plastic cage used on the bosch pump but I wasn’t happy with how it fitted. With the sock fitted, it was time to splice the wires to extend them to the bulkhead and plumb it all up before putting it in the tank.

It was then covered with fuel-safe raychem heatshrink.

The raceworks high-current bulkhead connectors were installed after drilling two holes in the lid, and then it was all secured, ready for install.

The old under-car fuel pump and filter were removed, and a new (stock spec) filter with the right AN fittings were installed in the original location.

The new 5/16" (8mm) hose was then run up to the rail, and the return hose was replaced too. Everything except the hose connecting the rail to the reg is new, and I'll do that last piece shortly.

After some swearing, the carrier was installed back in the tank, new hoses were connected and the filter, and new feed/return lines were installed. It's a bit of a pain to run the new hoses to the hard lines near the tank, but I'm glad I did given the condition of the old main feed hose. Tank vent hose looked in fine condition so didn't replace it.

I ran new 12AWG wire from the tank bulkhead connector all the way (~6 meters?) to the connector that originally powered the under-car pump.

I put some new fuel in and it started up first crank, and no longer dies after moving around like it did. So far so good. Noticed there’s less power draw on the electrical system too with the voltage it sits at idling now. Clearly having two high-pressure pumps was putting a bit more load on it, and a single pump removes a point of failure so that’s nice.

The best part? After some laps of the block, I realised the stumble I had coming onto boost is completely gone now, and it just freight trains. It’s completely different now I wonder how long it’s been on its last legs for. Very occasionally if I drop a gear and give it a boot my UTCOMP gauge would beep at me warning me of a lean condition (monitoring AFRs while in positive boost), at which point I immediately back off, but I thought it was possibly a lag between sensors. Fingers crossed that issue is solved too and that no damage was done to the engine because of that.

After it was all buttoned up, I had an issue where the fuel level was stuck at the previous position, and immediately I thought it might be an issue with the float inside the housing that got stuck. I decided to brim the tank, go for a long drive in it and by the halfway point about 100km in, it had sorted itself out and reads properly again! Feels good.

Edit: OH and there's even LESS cabin noise now, since that noisy-as-hell under-car pump isn't there anymore. I can't believe how much of a difference that alone made.

Aug-Oct 2024 - Diff Upgrades

It started off innocently enough, a decision to seek some 3.73 gears to lower cruising revs and thus cabin noise..

Then, since if I was going to change the gearing anyway, I bit the bullet on a TrueTrac and it was all downhill from there. I decided to give myself a couple of months to get this all sorted as I had no idea how long it was going to take.

The short of it was the following happened:

• Remove rear diff, take it to shop (I don't have the expertise, time or tools)

• Install Truetrac, 3.73 gears, and BNE tone ring

• Take out subframe and reinforce

• Replace dogbone bushes with PU superpro items

• Install BNE torque rods I bought years ago

• Slam it back in the car again.

I picked up the torque rods and tone ring back in 2021 and had been waiting (checks calendar) a while to install them.

Thanks to @Samman88 , while I was back in Melbourne, I picked up a set of 3.73 gears off him and we talked Volvos and whatnot for a while. Thanks again!

Once the bloke I decided to go with was ready, out of the car the rear axle came. The guy I got to do the diff was great - the only wrinkle in the process was that inner tube axle seals were unavailable locally from my searchings, so an order to GCP had them here within a week, so only a minor setback.

Edit: Oh! and for reference, the pinion seal was sourced from a bearing shop - SKF 15788. I also attempted to find the inner axle tube seals which were supposed to be SKF 14922 but I wasn't able to source these so that's why I went via GCP. There was also an equivalent National/Timken seal with number 1176 but I wasn't going to risk it given the local price was way more than sourcing seals via GCP.

I reinforced the subframe using the same methods most people do on turbobricks when plating up their 7/9 subframes - with the exception that I didn’t plate the upper underside bit as I wasn’t totally sure where the torque rods travel and figure that plating it on the amount that I did, added a decent amount of rigidity. I did the tacks with the torque rods bolted in, and the initial one towards the front I tacked in while in the car so I had the widths correct.

I also carefully slotted, welded and ground back the fingers that slot into the dogbone so they’re not just a folded up piece as well.

I got the same mob that did the tig welding for the exhaust to tack on the tone ring onto the housing, and they did a decent job. Welding it over the housing meant there was about a tooth gap, but it only reads a little under now, and with the spacer the diff guy put on it, it still reads, but I have to fix my speedo electronics still as it’s still as glitchy as it was.

Who knew they were red on the inside?

Getting the dogbone bushes out had me wasting a couple of hours with jaw pullers and sockets an vices, until I just sawed one lip off and pushed it out. I didn’t want to wreck them, but I got fed up. New ones pushed in easily and they’re snug, so I’m happy about that.

Bottom line - with the new gearing feels like this is what a M90L2 gearbox would have had from factory. I haven’t tested skids yet, and no additional NVH, so… win. It feels far less nervous while driving, which makes me less anxious behind the wheel, which is a huge plus. It wasn't a cheap endeavour, but I'm glad I'll hopefully never have to open it up again except for oil changes. I'm so glad this was done in time for nationals!