ClemSparks
ClemSparks SuperDork
7/1/10 12:01 p.m.

So,

I was disappointed last week when I fired the Volvo ('86 740 TurboWagon) up after a HeadGasket replacement and it was idling poorly and the engine was shaking all over the place.

I really, really thought I had my bases covered and the timing marks all lined up when I put it back together.

But like I said, the idle is rough and low as it sputters and shakes. When I rev it up a little it smooths out.

I also noticed that the crank pulley is wobbling. So I've got to go in and figure out what that is about also.

Whew...I hate it when I screw stuff up.

So...does this sound like a case of getting the timing off a tooth or two? The "smooths out when I get the rpms up a bit" part makes me think it's not crossed up plug wires (which I need to verify...hadn't thought of that until posting this...). The distributor/ignition timing is in the same place it was before the swap which should be good.

Anything else I could be missing?

Thanks,
Clem

Junkyard_Dog
Junkyard_Dog HalfDork
7/1/10 12:05 p.m.

The wobble is likely the pulley separating from the hub due to worn rubber. Common problem on the bricks. Do yourself a favor and spend the $80 for a new one. I got VERY good at swapping used ones before I learned that lesson.

Rechecking the timing shouldn't be that hard to do. Be sure your distributor is lining up correctly too. Luckily thats not an interference engine so having it off a bit shouldn't hurt anything.

shadetree30
shadetree30 Reader
7/1/10 12:49 p.m.

Have you taken a manifold vacuum reading? Might you have an intake manifold leak?

foxtrapper
foxtrapper SuperDork
7/1/10 1:15 p.m.

Second on the pulley separating. Don't wait until it lets go, that ruins your vacation trip.

Rechecking the timing should be very easy. Though from your description, I don't think that's your problem. With a tooth off it may be a little rough, but not much. Mostly, it'll be extremely weak. Sounds more like a cylinder not firing or a pair of them being cross wired.

ClemSparks
ClemSparks SuperDork
7/1/10 1:29 p.m.

I'll check the plug wires again to be sure.

About the distributor lining up...could I have gotten that 180 out and have it run like this? My brain is full today...but I think that if I had the cam timed right at top dead center (both valves closed) then my distributor should be good...right?

Come to think of it, it DOES sound like a crossed up pair of plug wires...

Thanks!

Clem

Junkyard_Dog
Junkyard_Dog HalfDork
7/1/10 1:34 p.m.
ClemSparks wrote: I think that if I had the cam timed right at top dead center (both valves closed) then my distributor should be good...right?

Yes. And if you were able to leave it in the head it should be right. Should be. But even if you didn't mess with it who is to say the PO didn't screw with it?

ClemSparks
ClemSparks SuperDork
7/1/10 1:42 p.m.

The PO probably can't hold a screwdriver by the right end, so it wasn't him.

I DID get to hear the car run briefly with the bad head gasket before I opened it up...so the distributor should be fine.

If not the spark plug wires, I'll reverify the timing belt (like I said, I reallly though I was good when I buttoned it up).

If not that...then I don't know what...

Clem

m4ff3w
m4ff3w GRM+ Memberand SuperDork
7/1/10 1:52 p.m.
Junkyard_Dog wrote: The wobble is likely the pulley separating from the hub due to worn rubber.

I went with a friend to buy an '88 Turbo sedan. When cranking the car, it sucked air in through the tailpipe!

That was a head scratcher for a bit. New crank pulley and timing belt and all was good.

Junkyard_Dog
Junkyard_Dog HalfDork
7/1/10 2:12 p.m.
ClemSparks wrote: If not the spark plug wires, I'll reverify the timing belt (like I said, I reallly though I was good when I buttoned it up). If not that...then I don't know what... Clem

tuna55 does.

tuna55 wrote: And yes, LS1 is a potential answer.
ClemSparks
ClemSparks SuperDork
7/2/10 8:08 a.m.

I rechecked the firing order. It's good.

I rechecked the timing belt alignment. It's good.

I took off the lower pulley and it looks like somehow it came off the keyway and that was what the wobble was (I don't know HOW I did that, but it's fixed now).

I fired the car back up momentarily without putting the timing belt cover back on (no radiator...just let it idle for a few seconds) and it's still doing the same thing.

I forgot in my original post that it is backfiring also...as part of the strange idle. The engine really does smooth out (hitting on all 4) when I rev it up just a little (I'd say it runs smooth over 1,000 rpm).

I took a little video and I'll hopefully post it in the next day or two to see what you all think.

Would a vacuum leak cause this? Because I'm new to volvos and may have gotten a line hooked back up wrong, or not at all...

Thanks,
Clem

Hal
Hal Dork
7/2/10 12:59 p.m.
ClemSparks wrote: I forgot in my original post that it is backfiring also...as part of the strange idle. The engine really does smooth out (hitting on all 4) when I rev it up just a little (I'd say it runs smooth over 1,000 rpm).

Both of those point to a timing problem of some kind. I don't know Vovlo's that well, but you mention vacuum. Is the distributor advance vacuum controlled?

I know a lot of distrbutors only go in the right way or 180 off, but there are some that can be put in just a little bit (one tooth ~10) off.

If you can change the inital timing, try advancing it 5* and see if that is any better.

ClemSparks
ClemSparks SuperDork
7/2/10 4:38 p.m.

[edit: See post below to see what the car is doing]

ClemSparks
ClemSparks SuperDork
7/2/10 5:02 p.m.

I've never tried photobucketvideo before...and I don't think that worked.

So here's some tubes of you: http://www.youtube.com/watch?v=7tZ0Fa8jWS0

(same vid in each link btw)

Clem

ClemSparks
ClemSparks SuperDork
7/5/10 11:18 a.m.

Bump...

anyone have any ideas?

Thanks,
Clem

SlickDizzy
SlickDizzy GRM+ Memberand SuperDork
7/5/10 11:24 a.m.

I don't know turbo bricks too well, but that seems to be running an awful lot like my Supra did when I had the distributor a tooth off after doing the timing belt.

Vacuum issue is also a possibility. Most likely an intake manifold gasket; it'd run better in the higher RPM's because the engine is pulling enough vacuum to nullify the leak.

ClemSparks
ClemSparks SuperDork
7/5/10 11:51 a.m.

The intake gasket is brand new. I might try doing the WD40 or Propane thing to see if I can locate a vacuum leak.

Thanks!

Clem

11110000
11110000 New Reader
7/5/10 12:53 p.m.

Sounds a lot like ignition timing is wrong. You've got the distributor on the back of the head, right? No way it can go in 180 out. You've got the hall sensor pickup in the distributor that can cause fits, but in my experience that usually shows up first at higher RPM/load conditions.

You could be looking at a case where the PO had the timing belt off a tooth, and the distributor was cranked off to compensate. Get a timing light on there, and see where you are - should be ~12* ATDC at idle.

Streetwiseguy
Streetwiseguy Reader
7/5/10 1:42 p.m.

I watched the video, but could not see the plug wires. They do not just go 1-2-3-4 across the cap. From drivers side, they go in the cap 2-1-3-4.

If that won't do it, unplug the mass air flow sensor and see how it runs.

ClemSparks
ClemSparks SuperDork
7/5/10 3:31 p.m.

Problem solved!

It was, in fact an intake gasket issue. Names will be changed to protect the dumbaz (loose nut behind the wrench...).

Thanks again!
Clem

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