So I have 2 questions, I am trying to slowly work on my 88' volvo with 370k miles and it will be a lot of work, I am changing trans oil to MTL today and all the engine/trans mounts when they arrive, than suspension bushings, etc...I do not want to do this again so I am using all OEM parts.

Today while I was under the car I noticed this plug is not plugged in, does anyone know what it is? Its kind of behind drivers tire...



And I found this coming from above the transmission..Is that a reverse switch? Which would explain why I dont have revers lights...






Also, I have a very slow oil leak, and it looks like its coming from back of the engine close to the firewall, there are 2 plugs...one is right next to sparkplug closest to the firewall and another one is above that one...Are those rear main seals, and can they be replaced w/o moving the engine. It looks like I have decent amount of space to feel everything.

Thx!

 

the reverse/park/neutral switch is in the shifter assembly. the wiring ON the transmission is probably the overdrive solenoid. WAIT, thats a manual transmission? ok, I'm not sure where the R switch is on those, and of course, there is no park/neutral safety switch.

the thing in the first picture is the brake proportioning valve. on a non-ABS car, you actually have 2 separate hydraulic circuits. one circuit goes to one piston at each front wheel plus a one rear wheel, the other circuit goes to the other piston at each front wheel, plus the other rear wheel. that way, if one of the circuits fails, you still have 50% of your braking force at /both/ front wheels, plus one of the rears.

the sensor thing there is a differential pressure sensor, it would light the brake failure light on the dash if the pressure in the circuits is different, so you know something is wrong with your brakes.

 

btw, Volvo manual transmissions use ATF type F, not heavy weight gear oils. assuming this is a M46 (4 speed + Overdrive), the OD unit shares oil with the transmission, and is a planetary mechanism much like an automatic.

 

So the first thing in the picture should be plugged in. Thx, I had no idea that 240 even had that.

2 and 3 picture is differential pressure sensor?

This is a m47. I got Redline MTL 75w90 and dificult shifting in 1 and second is muuch better now...Sad thing is that I only drained like 22oz of fluid or 650ml or .68 quarts. I hope trans is not leaking oil. I lifted both sides of the car and lowered it with the drain plug out to get as much fluid as possible, but thats all that came out in a pitch black color...Poor Volvo.

I got one engine mount and trans mount, as soon as the other one arrives I will change them too. Than suspension bushings.

And what are those plugs at the back of the engine, close to the firewall? They might be leaking oil...

Thx for responding!

 

you might just drive around a bit and drain it again, the new oil will mix with any remaining dirty old oil and flush it out.

re plugs, you mean the one on the back of the head and valve cover gasket? thats where the rear distributor goes on a 740/940... its a camshaft seal. plugs on the side of the block below the exhaust manifold, those are freeze plugs...

 

I thought about it too an I prob shouldn't have put redline first since its kind pricey but oh well...I think you have a good point I should drain it again and flush it out as much as I can.

Oh ok so thats where the distributor on 740 goes, I just saw pics online and thats exactly what I was talking about. I should be able to replace that, right? But there are 2 plugs back there so what is the other one?

Updatge: Oh I just saw how to change camshaft seal, got to take valve cover off..It seems pretty easy.