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(Not*) Mediocre 242

My brake pedal at idle was pretty stiff and my brakes struggled to hold the car back at idle with this torque converter. The camshaft really doesn't produce much vacuum at idle so I wanted to try adding a vacuum pump to my brake booster. Some P2 Volvos use a Hella UP28 vacuum pump and vacuum switch to supply the booster with vacuum so I figured I'd try that and see how it worked. I made a bracket and installed the pump and switch:

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Now the brake pedal is easy to press at idle and the brakes have no problem at all holding the car back. The pump only comes on when booster vacuum drops so hopefully this junkyard pump lasts a good while. If not I may get the Hella UP30 pump which is the next size up and has a much longer life rating.

I did make two brackets so I'll sell my spare one if anyone wants it.

I've also been working a lot on modifying my Motec firmware to work better with the CanTCU transmission controller. With stock Motec GPRP firmware, the ECU wants to control the whole shift itself which led to some overly aggressive upshift cuts and just not quite what I want. After my modifications I've now got it shifting much better and just doing what the CanTCU says. I'll have to take a video because it feels awesome.

Unfortunately I'm pushing a bit of coolant out of the expansion tank. My coolant pressure doesn't seem excessively high in my logs, but even after swapping a couple caps I'm getting some coolant leaking. I ordered a new head gasket and once that gets here I'll pull the head and take a look.
 
t8fanning said:
My brake pedal at idle was pretty stiff and my brakes struggled to hold the car back at idle with this torque converter. The camshaft really doesn't produce much vacuum at idle so I wanted to try adding a vacuum pump to my brake booster. Some P2 Volvos use a Hella UP28 vacuum pump and vacuum switch to supply the booster with vacuum so I figured I'd try that and see how it worked. I made a bracket and installed the pump and switch:
B57MIytl.jpg

Now the brake pedal is easy to press at idle and the brakes have no problem at all holding the car back. The pump only comes on when booster vacuum drops so hopefully this junkyard pump lasts a good while. If not I may get the Hella UP30 pump which is the next size up and has a much longer life rating.
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That 3-way device behind the pump. Is that the vacuum switch?
 
dbarton said:
That 3-way device behind the pump. Is that the vacuum switch?
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Yes. It's a switch and check valve. One port goes to the pump, one port to the intake manifold, and one port to the booster. Here's a link to FCP for the switch:

Vacuum Switch

Stiggy Pop said:
You could try a leak down test before you take the head off. I had an overflow tank split a seam up top near the threaded neck for the cap..
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I pressurized the cooling system without the cap and saw some coolant coming from between the hose and port that goes to the radiator. I have a brand new expansion tank coming and it will beat the gasket getting here so I'll put that on before I pull the head. I probably should do a leak down though.

cosbySweater said:
Are you using the stock Volvo expansion tank?
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Yep, the stock turbo one from 1982.
 
Harlard said:
Did your car use those ASS mounts back when I rode in it?
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I think so.
Stiggy Pop said:
Hope that heads ok 🤞
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Me too. I think it's the head gasket probably. I retorqued the studs again the other day and they took some additional torque so I wonder if it wasn't sealing properly. I probably need to crank it down a little more on the install with a new gasket, but I don't want to go much more than 95 ft-lbs.
 
all of my volvo expansion tanks have leaked. i double stacked gaskets inside a green cap and it has solved the issue so far....

what head gasket are you using the cometic or athena style?
 
t8fanning said:
Me too. I think it's the head gasket probably. I retorqued the studs again the other day and they took some additional torque so I wonder if it wasn't sealing properly. I probably need to crank it down a little more on the install with a new gasket, but I don't want to go much more than 95 ft-lbs.
Click to expand...
With head studs on the rally car we had to retorque all the time, basically after every single race weekend. Ended up going back to stock bolts (might be pushing it for you though) and no more problems with pushing coolant. This was with a composite HG btw.
 
t8fanning said:
I think so.

Me too. I think it's the head gasket probably. I retorqued the studs again the other day and they took some additional torque so I wonder if it wasn't sealing properly. I probably need to crank it down a little more on the install with a new gasket, but I don't want to go much more than 95 ft-lbs.
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Interesting, I hit mine when I was doing valve lash in March and nothing really moved. I don't run 30psi though :)
 
cosbySweater said:
all of my volvo expansion tanks have leaked. i double stacked gaskets inside a green cap and it has solved the issue so far....

what head gasket are you using the cometic or athena style?
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What expansion tank do you use now? Some metal one? I do have a brand new expansion tank on the way. I'll try that and see if the leak stops before I do anything with the head. I also use a black cap, maybe I should try a green.

It's funny because it first started leaking like two weekends ago after an easy drive to a cars and coffee. I only got into it once and didn't even hit max boost. I would have thought if it was a head gasket issue it would have happened on the dyno when I was doing multiple high power pulls. An expansion bottle failing on some random drive makes way more sense.

I use a Cometic .045" thick.
culberro said:
With head studs on the rally car we had to retorque all the time, basically after every single race weekend. Ended up going back to stock bolts (might be pushing it for you though) and no more problems with pushing coolant. This was with a composite HG btw.
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Interesting. I think I'm going to keep the head studs since I still want more power. Maybe I just need to add retorquing to the maintenance list, or maybe the head just is moving around and hasn't fully settled yet.

Stiggy Pop said:
Interesting, I hit mine when I was doing valve lash in March and nothing really moved. I don't run 30psi though :)
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35 psi now that my fueling is "fixed" ;)
 
dbarton said:
Sorry. Did you happen to test the vacuum on/off threshold for the switch?
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Unfortunately I didn't. According to this guy, the pump pulls ~27 inHg. He is using a pump from an S40, which is the same as the P2 cars though.

According to Hella, the pump does 500 mBar of vacuum in 4 seconds at 13 volts, but that's going to depend on atmospheric pressure and how much volume you're trying to evacuate.

I'd guess the switch turns off somewhere around 20 inHg.
 
I am using stock ones currently even though they leak ive been meaning to put a newer style 940 tank on there but both of my 240s will randomly push coolant. The om606 wagon has the double stacked o ring in the cap and it seems to be fine. The ls 242 will randomly do it, I can beat on it and nothing bad happens, then sit in traffic on a wednesday at 3pm and it will purge out, lol.

the black cap is like 70kpa and the green one is 150kpa iirc.
 
cosbySweater said:
I am using stock ones currently even though they leak ive been meaning to put a newer style 940 tank on there but both of my 240s will randomly push coolant. The om606 wagon has the double stacked o ring in the cap and it seems to be fine. The ls 242 will randomly do it, I can beat on it and nothing bad happens, then sit in traffic on a wednesday at 3pm and it will purge out, lol.

the black cap is like 70kpa and the green one is 150kpa iirc.
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Lol sounds very similar to what mine is doing. It's weird because my coolant pressure log doesn't seem to have any crazy pressures, any time I've seen coolant leave the tank, so it probably is just some leak.
 
bobxyz said:
What were you seeing for idle vacuum (or MAP) with the RSI stage 3 cam before adding the vacuum pump, and what are the VE's around idle?

[I'm still trying to make sense of the discussion in
https://www.turbobricks.com/index.p...-too-low-how-to-fine-tune-ms-and-b230.373271/
and would like another example.]
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With the RSI stage 3 cam it was right around 8 inHg and probably like 47-50% VE at idle . This is a different camshaft and I see like 1 inHg and 45% VE at idle.
 
t8fanning said:
With the RSI stage 3 cam it was right around 8 inHg and probably like 47-50% VE at idle . This is a different camshaft and I see like 1 inHg and 45% VE at idle.
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so, interesting my RSI head with the stage 3 cam pulled more than 8in at idle, I'd have to go back in time and look for values but I know it dropped with the big Kyrk cam. And now with the same Kyrk cam as you I'm at 8in at idle (watched it on tuesday with your car in mind). I know we both timed the cam to Reine's specs... still don't understand the difference there. My pedal definitely gets stiff around idle but it hasn't been enough of a problem to go after a solution.
 
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