Replaced head gasket and it runs really bad now.

[Phreon]

Hi Folks,

I had to remove my head due to the dreaded timing chain profile gasket blowing on my '93 318is. The car ran great before but now that I have it all together it has no power, will not idle, and is popping back through the intake manifold mostly when I let off the gas.

I did not unhook the battery because I did not want to loose the computer settings and I thought it would run well after I put it back together. Not so much.

It almost feels like a dead cylinder. Any ideas what it could be?

Thanks
P

[flyinglizard]

It may take 5 to 10 min to run right after the lifters have bled off.  The first one I did scared me  after restart.  I have done two in the last month and they both did the same thing.

  How  convinced are you that the cams are right?

[Phreon]

Hi flyinglizard,

I removed the head with the cams in it. I never removed the cams so the lifters should probably not have expanded.
I checked and rechecked the cam timing. Used a straight edge to align the rear cam squares and brought the engine to TDC before tightening down the cam chain gears. I had marked the gears and the cam with a punch before I took it apart. The dots I made lined up, the engine was at TDC, number 1 cylinder cam lobes were pointed to each other, and the cam squares were flat.

I am not feeling real good right now after all of the work. I ran it for about 5 or 10 minutes around the block. Ran bad. I will run it tomorrow and see if it is any better.

Thanks for the reply.
P

[flyinglizard]

The valves bend very easily, if it was set down on the face at all.  Compression check it.
     I remove the cam towers.
   But you could maybe cheat part of the job by lifting the head up enough to swap the gaskets.  Done a lot on the VW and old Dodge 2.2. Wrap heavy wire around the cam, lift with a picker , swap gaskets, set it back down.  About one hour with fluids.
   I would guess that the BMW flat rate guys did it this way when BMW did these under recall.

[Phreon]

Before I placed the head on the block I moved the pistons down in the cylinder so the valves would not hit.
While I was working on the engine the head sat on two 2 X 4 blocks.

What is the procedure to do a compression check? Do you have to disable the ignition to protect the coil packs?

Thanks
P

[nicknikolovski]

Start up engine and apply a small amount of throttle Once you start seeing the engine warming up, rev the engine at 3,000 rpm to help bleed out the lifters. Even if you didn't remove the camshafts, trust me lifters will bleed out the oil back to the sump. Also remember after a head gasket replacement, compression is not the best due to all the crap in the cylinders. It sometimes takes a fair few cranks of the engine to get it going.

Did you turn over the engine by hand to check your timing?
Are the ignition coils firing to the correct cylinders through the ignition leads? (Maybe mixed up)
Are there any vacuum leaks and have you checked over all your connections (ie hoses, wiring etc)

And I know it may sound like a good idea, but I wouldn't hang anything by the camshaft. There should be engine lifting brackets on the head. Use them.

[Phreon]

Hi nicknikolovski,

Thanks for your ideas...

Before I replaced the head I thoroughly cleaned the cylinders and head and after installing the head and timing the cams I rotated the engine several times by hand.

I had a plug wire mixed when I first started the engine but I straightened that out.
There could be a vacuum leak but it is impossible to see under the intake manifold on a '93 M42. I will check again.

I handled the head by the thermostat hole and the rear edge, not the cams.
My concern is that it backfires through the intake frequently. That sounds like an open or sticky intake valve. I would have guessed a vacuum leak due to the loss of power and the stalling rough idle but the backfires are worrying me.

Started it up this morning with no change. It idled a little better, due to the richer mix at cold start I think. (Florida is not too cold though.) But then ran bad again.

I can see the cam lobes through the oil cap on the valve cover. At TDC the lobes point to each other so it looks like the cams are timed OK. Will a couple of degrees make it run this bad?

P

[Phreon]

Problem Solved.

I had spark plug wire 1 and 4 mixed. Turns out you can drive it that way. :-)

It runs great.

Thanks to all for the suggestions. If I can figure out how to post a How To with pics, I will. Let me know if anyone knows how to do it and keep the pics next to the correct text.

P

[RED IS 91]

You need to set up an account on photobucket or equivalent then upload your photos and link them to your post.

Look in here
http://m42club.com/forums/faq.php?faq=vb3_board_faq#faq_vb3_reading_posting

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