Vacuum prob: No Start

[graphikg]

I replaced the HG in my S50, along with timing chain cover gaskets, and Vanos gasket. I didnt replace the V cover gasket, and Intake manifold gaskets.

So after doing the work, my car starts up and has this rough idling, plus surging here and there. It is hesitant when revved, and when you let go of the accel, the rpms drop to below idling point (almost to the point of the car dying) and then the rpms go back up to normal idle level. The car sometimes dies when accelerating or letting go of the revs until it drops before idle and dies.

After leaving the car just sitting for a few weeks, I tried to turn it on and now it doent even turn on. It tries, rumbles a lot trying to start and dies. It almost feels like the car is off timing - but it should not be because the timing should be spot on.

I think I should replace the V cover gasket, intake manifold gaskets, and maybe do a valve adjustment. What do you all think.

OH and..... Yes I did spray carb cleaner everywhere and I could not find where the vac leak was that way. Sprayed it everywhere.

[7pilot]

Pull the intake manifold.
resite the gaskets and smear a thin coating of grey import application silicone.
Make sure any vacuum ports on the intake manifold have hoses or are sealed.
Make sure any holes on the throttlebody and TB elbow are sealed.
make sure to reconnect the fuel pressure regulator.

m

[newman]

Use an anaerobic sealant on the intake flange, like loctite 515

Can I ask why you replaced the headgasket? Was it to correct a blown one or preventative maintenance?

[surebimmer]

Are you sure the motor is timed right after putting the head back on? I would replace the intake manifold gaskets and valve cover gaskets. You can't do a valve adjustment on hydraulic lifter cars.

[skatingzooyork]

Sounds exactly like my m50 when I first got it. I had a vacuum leak under the middle of the intake manifold...

[graphikg]

Thanks for the help guys. I was leaning towards the I manifold, but now you are only convincing me only more. I am going to just get new intake gaskets, new V gasket, and find out what the deal is with that fuel pressure regulator. I think these are all things I can do. But where is the fuel P regulator?

Newman: I replaced the HG because I took off the head to replace the timing chain cover gasket. There was a mystery leak from my car that looked like it was coming from the spider hose where it meets behind the oil filter housing. What it ended up being was a bad timing chain cover gasket (and the people I bought the engine from said it was rebuilt - heh). In order to change that gasket, I hab to take off the head and thus replace the HG. Now that everything is timed and together - I got this vacuum problem. I am pretty sure the timing is right because the car jumped out of timing, and we did it again carefully making sure everything was in place.

Any other suggestions are welcome!

Especially from the guy with an R34 motor in his e30! :) HAHA - Great build man! and great dancing too - LOL

I will keep you all posted.

[dsobering47]

As already stated, if your timing isnt off then it sounds like you have a nice vacuum leak. I wouldnt worry about your VC gasket as much as your intake manifold gaskets...

[Mossman]

You also said you might adjust the valves which is concerning cuz from doing the head you should know they've got hydraulic lifters and there's no adjustment possible.

The elbow thing that goes into the bottom of the intake, part of the idle valve plumbing, check that. Huge hole that could make for a huge vacuum leak, only one that you can't see too easily.

[graphikg]

Thanks for the advice Mossman... Silly mistake about the valve adj - wrote it late and I think I was thinking M20 for a sec. As for the elbow tube that goes to the ICV under the manifold, I think that is atleast eliminated because we made sure the clamps were nice and tight on both ends. I am really leaning towards it being the intake manifold and am going to try it next wknd when the parts come in.

Does everyone else promote using a silicone or sealant for those I Mani gaskets? Would that make a more sure seal?

[Mossman]

New intake mani seals protrude a good amount from the mani and are nice and squishy, I highly doubt you'll have sealing problems.

I wasn't referring to the hoses attached to the elbow thing, (although you should check those too), but where the elbow snaps in to the intake. It's got a chintzy tab that holds it in that is quite often broken and its just being held in there by friction on the o-ring. Check that o-ring too.

[graphikg]

Do you mean this one? http://www.pelicanparts.com/cgi-bin/...11611738629-M9

[dsobering47]

I had a throttle body gasket slip out when I put an M50 intake manifold on my buddies Z3, def check that too.

[graphikg]

From the sounds of it, seems like it is an issue from the mainly intake manifold, or intake manifold areas like the intake, ICV or throttle body. Are vacuum issues from these areas not uncommon when people take off their In Mani and put it back on?

[graphikg]

I posted in BFc as well, told them the same situation. They are telling me that it could be as serious as bent valves. But the car was running for some time, just now it does not start. I am going to try starting it again tomorrow.

[7pilot]

I posted in BFc as well, told them the same situation. They are telling me that it could be as serious as bent valves. But the car was running for some time, just now it does not start. I am going to try starting it again tomorrow.

Before you try to restart, put a socket on the crank nut and try to rotate the engine by hand, clockwise.
If it stops with a clunk or heavy tap sound, the news will not be good.

m