3.4 DOHC Fuel Pressure Regulator Adventures and questions, saving my brake booster?

[GnatGoSplat]

FPR on the 94 convertible 3.4 DOHC went bad, left my wife stranded at work. This car leaving my wife stranded at work has become way too common.

 

It had run (badly and noisily) when she called me, wouldn't start when I got there. I tried way too hard to get it started, hoping to limp it home and avoid calling a tow truck. Thought it might start because sometimes it seemed if I cranked long enough, it acted like it might. Didn't know it was the FPR at the time. Assumed it was ICM until I saw a fuel puddle under the car, then assumed it was a fuel line (thought I could have nicked it working on the coolant quick disconnect directly under them).

 

Got it home, ran fuel pump prime looking for the leak, and saw fuel coming out the plenum. Opened the throttle and it seemed like a gallon of fuel poured out.

Pulled the plenum, saw it flooded the intake too.

Notice the port at the bottom is full of fuel.

 

Yep, brake booster full of fuel too. D'oh! Used a barely functioning MityVac to try suck out as much as possible from both the intake and booster.

 

 

• It never acted hydrolocked, though it did seem hard to crank at times, like the battery seemed to get low pretty fast. Could have just been a cheap Walmart battery though. What are the chances of mechanical damage to rods or valves?
  
• Broke a couple of dry-rotted rubber bits getting the plenum off. The elbow at the front valve cover that goes to the PCV, and the rubber connector at the rear valve cover that connects to the plastic vacuum harness. It's odd-shaped, can a piece of regular hose replace this?
  
• LIMG is only 3yrs old, though car has a mysterious coolant leak dripping off driver side rear subframe that could be the LIMG. No signs of coolant in the valley or anything. Replace it anyway?
  
• Was planning on replacing spark plugs, plug wires, valve cover gaskets, and PCV while I'm at it. Anything else I should replace?
  
• Guess I'll just have to cross my fingers on the booster. I know fuel kills them, dries out the rubber. Booster warranties expressly say fuel gets in it, warranty void. I don't suppose there's such a thing as something I could spray in it to counter-act the drying effects of the fuel?
  

 

Sure wish I didn't try so hard to get it started and flood the entire intake and booster. Still kicking myself over that. Had FPRs go bad on all my other pushrod W-bodies, but never tried real hard to start them because one died in traffic and I didn't have time to try, and the other died at home so I didn't need to. It's going to really suck if I have to replace the booster.

 

Any thoughts, words of advice, sympathies? Maybe suggestions on things I could say to a wife who thinks it's stupid for me to put any more work into the car and is trying to convince me to scrap it? Or maybe I should just give up on it? It was her DD and she hates it. Very much.

Edited October 31, 2014 by GnatGoSplat

[19Cutlass94]

Shawn, I believe I still have my stock brake booster from my car. I can check to see if I still have it, and if you need it lemme know.

 

Did you take the plugs out and try and spin it over?

 

If your planning on replacing all that, I would just bite the bullet and replace the LIMG anyways. I mean your basically there. Nothing worse than not doing while almost there, then have to do it soon after and take it all apart anyways.

[GnatGoSplat]

Thanks for the offer, though I actually have an extra booster from a 96 Monte. Don't know if it's any good though, how do you test them? Too large to test with a hand vacuum pump (tried it). Tried to see if there was any more fuel in it and managed to suck up a lot more, but it's hard to control where the hose goes once I stick it in the hole. There's probably still a lot of fuel left in it that I don't know how to extract. Mainly just dreading having to replace it. Seems like a LOT of back-breaking work and having to bleed the brakes. Might have to even pay someone to do that as I don't have any method to bleed the modulator. Gonna hope that it doesn't die and will last at least till we get a new (to us) car. Assuming I can get the engine running good.

 

Took the plugs out to try see if it'll crank, and pulled off the rear timing cover to make sure belt is still intact (it is). Couldn't get it to crank, battery might be too low. I've got it on the charger right now. It's too tight a space to get my wrench on the crank pulley like I'm able to do on the pushrod engines. I noticed the plugs were very oily on the outside, I guess the middle gasket in the head needs replaced too, but I assume that's a huge undertaking?

 

Yeah, I was leaning towards replacing the LIMG, for the 3rd time.

 

UPDATE: It charged up enough it cranks on its own. No weird knocking sounds. I had dropped the plug wires back into the holes to keep crud from falling into them and didn't think to remove them. The engine built up enough pressure to blow them all out of the holes so I think that's a good sign that I probably have pretty good compression.

Edited October 31, 2014 by GnatGoSplat

[19Cutlass94]

You dont need to bleed the brakes when changing the booster. Its actually fairly easy to do, just takes a little bit of time. Unbolt the MC, pop the rod off the brake pedal, and twist the booster off, thats it. Just support the MC, and youll see a hook that the booster twists into that locks it in place.

 

 

As far as the engine work on the DOHC, I dunno, I never messed with one and dont ever plan on doing so. Id just let the battery charge, pull the fuse for the fuel pump, and let it spin over and blow everything out of the cyilnders. Then go from there.

[GnatGoSplat]

That would be great if changing the booster isn't that bad. The MC can move out of the way despite the brake lines being metal? Did you unbolt the brake lines from the frame? Looks like it might have to come forward quite a bit for the booster to come out. Not sure that the MC can even come forward very much on the 3.4 DOHC because the fuel lines are in the way. Also not sure if the booster can clear the plenum if it's re-installed. Totally not wanting to pre-emptively replace the booster before I know it's bad/gonna fail, although I guess I probably should.

 

I looked more closely at the heads, and the upper part is the entire cam carrier, so not gonna bother changing the cam carrier-to-head gasket.

 

Updated previous post with the results of cranking it. Engine itself seems OK mechanically.

[19Cutlass94]

I didn't unbolt or loosen any brake lines. It actually has a lot of room to move without bending any of the lines. If your brake lines are rotted, I dunno if I would suggest it. But the MC, doesn't need to move very far to get the booster out.

 

 

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[Nas Escobar]

I've had a 3800 in my Camaro flood itself with rain water once since for some reason, there is a leak on the plastic cowl joint. It actually pushed all the oil out. It was actually quite a mess to clean up. I think because of this, I've lost oil pressure. It used to always run at a solid 60, now it runs a quart below the 60 mark. I've been told to swap out the oil pump, but ehh seems like its' a bitch to do.

 

Anyways, just thought you should be aware of that issue (may lose pressure). Other than that, if it doesn't start it doesn't hydrolock AFAIK. I know most hydrolock issues come from the car running when water goes in. Your starter may have taken a beating though, and I would have the CCA rating checked on that battery (get it tested). My battery on the Camaro had 300 CCA when it was supposed to be 750 so it would sometimes take a while to crank, and other times it would go dead as soon as I turned the key. Interestingly enough, it did start when I shook the battery.

 

I would also do the LIM just for safety. It's already there, it's only 12 bolts, why risk it being bad when you can assure it being good? I would also check the vacuum lines and the coolant lines. Don't forget to swap out that O ring where the plenum meets the engine. That fucking O ring leaked on me and it took me a while to figure out that it had to be changed. -____-.

[Schurkey]

First Guess: Once you replace the booster, you'll discover that the brakes are twice as good as what you're used to.

 

http://www.w-body.com/showthread.php/32510-Hard-brake-pedal-no-stopping-power

[GnatGoSplat]

Maybe so, although they were more than adequate before. Man, I'm really hoping I won't have to replace the booster. Gonna try fixing the engine first and then deal with the booster if turns out I have to.

Ordered all the parts this morning.

Still can't find anything to replace the rubber ends of the plastic vacuum harness though. Can't find any place that actually has the vacuum harness for sale either. Part #24503665. None of the Google hits has a price or "Add to cart" button.

 

Guess I'll have to cobble something together like Ken mentioned in this thread. http://www.w-body.com/showthread.php/53544-Hard-lines-for-LQ1-***Need-Part-number***

[George]

Quote from Gnatgosplat: Broke a couple of dry-rotted rubber bits getting the plenum off. The elbow at the front valve cover that goes to the PCV.

 

This seems to be the most recent post about the Elbow on the valve cover that goes to the PCV.

I found this at O'Rieleys yesterday and it worked great.

 

 

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[Schurkey]

I have orange silicone 90 degree spark plug boots crammed into place on both of my Luminas. About fifty cents each. They've worked fine for years. Seal nicely to the tube and to the nipple on the valve cover.

[GnatGoSplat]

This seems to be the most recent post about the Elbow on the valve cover that goes to the PCV.

 

Thanks, I actually had picked up a similar part, Dorman 47029 which works perfectly as well and is $2 cheaper, but doesn't come with the straight part which I didn't need. Although best thing to do would have been what Schurkey mentioned...

 

I have orange silicone 90 degree spark plug boots crammed into place on both of my Luminas. About fifty cents each. They've worked fine for years. Seal nicely to the tube and to the nipple on the valve cover.

 

Yep, 90-degree spark plug boots would have worked perfectly. I figured this out days after I'd bought the Dorman part, but I realized the 90-degree spark plug boots on my old plug wires would have worked perfectly. They would have even worked better, actually, because the silicone will probably last much longer than whatever rubber the Dorman parts are made of. Wish I'd realized that sooner, could have saved myself $6+tax and the warm fuzzy feeling of reusing something that would normally be thrown away.

[crunkGP96]

Ok , I’m changing my brake booster. How the hell do you take that pin off from the brake pedal? It’s so tight in there!! 

[crunkGP96]

Btw I had the same exact issue that was in this thread. Brake booster is the last thing I have to replace lol 

[crunkGP96]

Finally got the damn little pin off with some needle nose vice grips. The booster is just held with the two nuts and pin from the brake pedal? Im asking because I’m turning it like it says in this thread and it’s not giving. 

Edited October 27, 2023 by crunkGP96

[crunkGP96]

This is an extremely tight fit. Can’t get it out. Now I know why people hate working on these cars 

[Schurkey]

The booster has to twist counter-clockwise from under the hood to release.  (Clockwise from the driver's seat.)  There's a lock-tab that supposedly has to be pushed, and then the booster twists and falls off.

I made a tool to turn the booster, and brutalized it enough that I never did deliberately "release" the lock tab, which I couldn't get to anyway.

Tool is ordinary steel channel, (angle-iron, or even flat steel bar would work as well.) three holes drilled.  Center hole tapped, ran a flange-head bolt into it, cut off the excess threads from the rear, and welded the M-F'r into place.  Drop the tool over the master-cylinder retaining studs.  A long-handle ratchet and socket on the bolt head is enough to turn the booster.

 

 

Close-up of the tapered slot that the lock-tab engages.  Good luck getting to it.  Which is why I just cranked the booster enough to pop it free.  As you can see from the shape of the slot, you have to turn that side of the booster "down" to free the lock-tab on the booster from the bracket on the firewall.

 

Lock-tab is easier to see on the "new" booster, left.  Hangs straight down from the lower right rivet, in the photo.  In this photo, the boosters are rotated 90 degrees, the lock-tabs should be horizontal, not vertical.

 

I replaced the booster on both my '92 and my '93 Luminas.  The brake-light switches at the brake pedal were different.  Had lots of trouble getting the '92 re-adjusted.  Had to completely remove the switch and re-set the position, install it, and THEN it self-adjusts to whatever it's supposed to be.  Took me hours to figure it out.  The '93 was "improved" and I don't remember it being any particular problem.

As alluded to earlier...I'm convinced that 80%+ of the complaints of poor brakes on first-gen W-bodies is due to faulty boosters that only partially work.  There's still some "assist", but not nearly what it's supposed to be.  And the boosters pass all the usual tests, they're just under-powered.  Replacing the boosters on my two cars made a HUGE difference in the braking power.

Edited October 28, 2023 by Schurkey

[crunkGP96]

I got it off and getting the new one In now as I write this. NEVER AGAIN lol.  I used this to get it loose, slowly hitting it with a mallet. It fit perfect in between the two bolts lol

Edited October 28, 2023 by crunkGP96

[crunkGP96]

The tabs on my 95 look different. It was pretty easy to slide back in and lock it in place. That tool you made was something like  what I was thinking before I found the pull bar hanging in my garage. Nice work!