Discussion in 'General Discussion' started by zzyzzx, Apr 10, 2008.
So, I had the valve seat drop in the no.2 cyl last year. When I rebuilt it, I only replaced the no.2 piston, but did rings on all four. Now it seems like I have a nice new engine vibration. It came on gradually, I never even noticed it until I fired up my parts car last week and realized how much smoother it ran than my DD. I'm thinking now that I want to go through and replace all four pistons and see what happens. Am I on the right track here?
Probably something much simpler. look to engine/tranny mounts, plug wires, idle speed, ect. There is a factory service bulletin pertaining to idle vibration issues on these cars.
The factory TSB is rather involved, realigning mounting holes and motor mount issues. I'll look at the other things you've listed though. I changed plugs, wires and the coil pack when I rebuilt the head, so I doubt they are the issue. Motor mounts I've not looked at yet. I did the rebuild in the car so I only messed with the top mount. I plan on replacing as much rubber as I can this spring. I hope that cures it
You must have had the pistons out, to replace the rings. If they were all free to pivot/flop back and forth on the wrist pins, thin I doubt they would contribute to vibration at an idle. The factors mentioned above by millball would be my first suspects.
I would also want to ensure that the cat converter was attached to the brace on the back of the oil pan, which it would have been originally.
Did you do the repair work yourself? When the pistons were out, if any of them were the slightest bit 'stiff' when pivoting on the wrist pin – then I would definitely dismantle the engine, and remove the pistons, to either get used ones that are free to flop, or new ones, and maybe replace any affected con rods too. This would be to avoid a piston fracturing, which becomes a “communicable failure”.
I did the work myself, the only stiff wrist pin was on the #2. I replaced the con rod and pin with the piston. I do not like communicable failure. It will be warm enough to work on the car in a couple months, should I pull from the bottom and pull the crank, or from the top? The bottom seems more logical to me. Also did rod bearings then but never touched the crank.
Did you have the valve seats done at 83k
If you know the pistons were free to flop on the wrist pins, and none of the pistons you put back in had enough distortion to have the piston rings stuck in the groove, then I would think you did a good job. Not sure why you would want to do it again. I dont think its feasible to remove the crank from the bottom, due to the need to disconnect it from the flywheel (or flex-plate) and to slide the oil pump casting off the end of the crank. But its not possible to get the pistons out by pulling them down. The web for each of the main bearings is wider than the distance between cylinders, so presents an obstruction for each piston descending.
In all of my rebuilds I replaced the crank bearings; just because they were facing up at me on the workbench. I think there was only one engine where the bottom half of the bearings looked worn much – being that I could see some copper where the soft-metal had worn down. But as far as I know, all the cranks were still easily within specs for continued use. They looked so good that I only mic-ed one or two of them.
I like your question about the background on lilRedwagon92 head and its valve seats. I was wondering myself.
I put a junkyard head on my 94LX when fixing up the valve seat drop it had when I bought it. I may replace that head this summer, just to get a head on it where the valve seats Have been replaced. Its been 9 years and 90,000 miles since its rebuild, and we use that car for long drives across the USA and I would much prefer to fix it ”at my own place and my own pace". It would also give me better access for adding an oil pressure gauge; which I have been wanting to do to one of my Escorts.
I dont know that the newly installed valve seat inserts are some different technology; I suspect sintered metal inserts are what the industry is using. But at least they will be about 25 years less old, and hopefully represent better manufacturing technology.
It's not that I want to do it again, I'm just interested In reducing the excessive (I think) vibration. I may have to do the TSB.
I didn't even consider obstructions from the crank webbing. Good point. I drive mine from here to California and back twice a year. Don't want it to fail down there either.
We expect to be driving through Oregon, going from Long Beach to Seattle, sometime in early April. We have 2 grandsons there. My sister and her hubby live in Long Beach. We also have friends in Tijuana to visit. I think we would be starting from our winter place in S. Texas; probably driving our 94LX wagon.
Honk when you drive by, I know there are a few forum members on the I-5 coridoor
Mine dropped 20 minutes ago, one and three cylinder looking at it from the bumper.
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Gonna pull the head, if the post one are fine, I'll pull a junkyard head, clean it up and rebuild the head, and sell the car, if the pistons need done I'll sell it for parts.
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If any piston shows any pockmarks, you really need to remove the pistons to check them for damage. I mentioned this in prior postings to this thread. If there are any pockmarks, a replacement new or used piston would be essential. I have rebuilt two that had dropped an inlet valve seat – had to replace two bad pistons in each motor, or else even with the rebuilt head, the piston would have failed by fracturing, and causing worse damage to the block. The engine might run nicely, but I doubt it would last even 1000 miles – before the piston died, due to the distortion. And of course you need to flush out all of the metal particles from the intake manifold.
The cylinders were undamaged. I got them honed because I was installing new piston rings.
Well I thought I did but apparently the shop only cut them not replaced, then found out today as I pulled the block apart it blew up piston #4
That looks painful yet beautiful at the same time. How's the cylinder wall look?
To the naked eye it doesn't look bad, I didn't see any marks or scratches on the walls, and surprisingly it actually still has the cross hatches in the cylinders
The rebuilt heads with the upgraded valve seats are pretty cheap on ebay, and the seller takes damaged heads as cores.
Having the factory hone marks still visible from about 1/4” below the sweep of the top piston ring was what I saw in each of the eight 1.9L engines I have rebuilt. This was the case even where I was fairly sure the engine had traveled past 200k miles. And neither of the engines which had dropped a valve seat insert had any visible damage to the cylinder walls. I put original used pistons (with new rings) back into the engines, except for where I had to replace a pair of pockmarked pistons. I had each block honed, so the new piston rings would seat-in.
Modern engines seem to exhibit almost no cylinder wear. I suppose this is due to better oils than in years past, and fuel injection which prevents the washdown of the cylinders by raw gas when carburetors were in use.
The 1960s engines I first started working on would all have a huge ridge at the top due to high cylinder wear.
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