2&3 Not Firing Well, Engine Rocking

[ozmington]

OK boys and girls, I need your help again.

A quick history. Purchased 1981 124 from someone I work with who owned it for about 10 years as a weekend ride. He handed his wallet over regularly to his mechanic and over time, most of the major things were replaced. Engine rebuild about 6 years ago. About 2 years ago, FI was removed and replaced with Dual Weber 40IDF's. I replaced fuel tank, some gaskets, eliminated vacuum leaks, cleaned grounds, electric looks good, have basically worked my way through most peripheral systems. Carbs have been studied, and re-studied and appears in good order.

While the engine runs, doesn't stall and can get me down the road and even to work, it doesn't run well. There is an overall “rocking” appearance to the engine in idle and the idle speed which is also set a little high to compensate. I know the carbs need additional synching and an be fussy but hold that thought because........

Replaced plugs to find that 1&4 looked a nice light tan/brown but 2&3 were quite dark and rich and a little oily, basically fouled.
I pulled the wires one at a time off 2 & 3 and hear little, if no, change in the engine. But when I pulled #1, engine died completely. So there's the problem, 2&3 are not firing well, if at all.
I swapped out the wires with 1&4 with no change so the wires must be fine.
Pulled the dist cap. Visibly all looks well. No cracks, no excessive wear, no burns, etc.
I pulled the wires from the cap side and can see spark when held near each connection site.

Obviously, I want to start with the small stuff and work up (hopefully I don't have to). If there dist cap/roter visually look fine, is there ever a need to change them? What else could be the issue here? I put a timing light on it and it's pretty darn near 10BTDC. I'm baffled as it runs without any other peculiarities beside the lack of HP and the “rocking” and no major bizarro noises except a mild knocking noise from underneath the car because the engine rock is causing other banging like from the exhaust. Nothing strange on the top side of the engine.

Thanks in advance for your help.

[majicwrench]

You need to check compression to start with.
Keith

[ozmington]

Yep, I need to find a resource to do this. In the mean time, and as a curiosity, what is the best way to test the coil for good, consistent output?

Deb

[So Cal Mark]

it's not the coil, start with basics; which would be compression first. Without compression, nothing else really matters

[majicwrench]

ANy parts store will have a nice, cheap comp tester. Need not be fancy. You really don't care if its a few lb pressure off. What you are looking for is low low cylinders.

Listen to Mark, it aint your coil.
Keith

[maytag]

Mark and Majic are correct..... but if you're bound a determined..... pull the wire from plug 2 or 3 and put a screw-driver in it. then lay the screwdriver on the motor, with the metal part only about 1/8" away from a ground. And then crank the motor. You'll see the spark jump from the screwdriver to the ground.

but this is just for fun... 'cuz I'm with Mark and Majic: ain;t yer coil.

What neither of them have said 'cuz they hate jumping to conclusions as much as I love jumping to conclusions, is that two cylinders, right next to each other, with plugs that are "oily" usually means you'll be pulling the head.

Do yourself a favor and get the compression test completed.

[ozmington]

Just picked up a tester kit....stand by for further announcements this weekend.

[ozmington]

OK. Zero compression on 2 & 3 (thank you Harbor Freight). Bummer but at the same time, we have a direction to go in now.

Hubby is an experienced hobby mechanic but I've kept him at arms length til now. We pulled the valve covers, nothing seemed inappropriate to him there. He's got me pulling the oil pan to check it for flotsom and jetsom although he's not expecting to find anything, (probably keeping me busy while I wait for the gasket set).
No blowing any smoke. Good compression on 1 & 4.
Considering valve seats and springs as a possibility.
Thoughts anyone???? Don't really want to take apart more than we have to.

Good times......
Deb

[So Cal Mark]

don't waste time pulling the pan, just remove the cylinder head and all of the mysteries will be revealed

[ozmington]

Thanks!!

[mPedro08]

My guess is blown head gasket, anyone check the oil/raditator water?

As Mark said pull the head not the bottom. With that carb conversion...it was done for power and I'm going to guess an overheat...warped head and subsequent head gasket failure...which means you need to have the head properly looked at prior to re-installation.

Any takers?

mP.

[ozmington]

Well, oil looks good and free of any coolant so that was a good thing. Also, it was suggested to me that I'd probably be left with some compression in these cylinders if it was a head gasket and I've got ZERO.

Make a difference in the thought process??

I'll start tearing it down this week so we'll know soon enough but if anyone's a betting type............???

[So Cal Mark]

were all 4 plugs out when you did the test? If so, put #3 back in and test #2. It's common to blow the gasket between cylinders and not into the water jacket. You could also have some bent valves. If the gasket is blown between the cylinders check the block for flatness in that area. The flame traveling between cyls can act like a cutting torch and burn a channel, ruining the block. I'd hope for a couple of bent valves personally

[majicwrench]

I'm betting blown gasket. Looking forward to pictures regardless. Yank head.
Keith

[ozmington]

OK, head yanked (te he he)

Alrighty then......yup blown between 2 & 3. The head is not warped per flat surface, corner to corner and a feeler gauge. This includes the space between the cylinders where the gasket blew so I think I'm alright. There was a darkening in that space on the surface but it feels otherwise smooth. Should seal back up. This is good news.

I'm going to look at this as an opportunity to replace all the mismatched bolts, whatzits and whozits that the PO left behind. It's been a bummer thinking about all time wasted leading up to it but considering this is my first "big girl project", it was a chance to learn a lot. I'm going to also take the opportunity to replace the starter since it's also been fussy lately and it's now fully accessible. Thanks to everyone who helped!

Two new questions. 1. The shop manual shows an additional guard of some type underneath the main plastic belt shield. I don't have this. Is it something that I should go out of my way to replace? I'm guessing it's to prevent additional damage in the event of a belt failure.
2. The last picture was taken underneath the passenger side and is a side view of the transmission housing. What is this broken bracket from??






Now..... I'm off for a manicure. Girls gotta do what a girls gotta do