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Re: Trying to change a Piston with Engine and Crank in Place (TD)

Subject: Re: Trying to change a Piston with Engine and Crank in Place (TD)
From: Frank Krajewski <>
Date: Fri, 10 Dec 1999 10:13:37 -0500
Having just completed the task I can assure you that it is a real knuckle 
to compress the rings when reinstalling the pistons from beneath but I don't see
how you could do it any other way.  I used small blade screwdrivers and gently,
tenderly, gingerly was able to compress the rings and reinstall the piston from
below. I don't know how you could install them from the top and reconnect the
wrist pin without inserting the piston so far down that the rings would unseat
anyway. Am I missing something? I plead Polishness on this one.
Frank "Swamp Yankee" Krajewski wrote:

> As several list members advised, I was able to remove the piston and rod from
> the bottom past the crank. I found this had to be done on the camshaft side
> of the engine and it's a bit tricky. The crank rotation, piston and rod all
> had to be manipulated in order to "sneak" the assembly out. Once out I could
> not get a socket to go over the wrist pin clamp bolt because it's so close to
> the rod. Horst Schach in The Complete MG TD Restoration Manual suggest using
> an open end wrench, but my wrench couldn't get a good enough grip on the bolt
> and it started to round off the head. So next I tried grinding down the
> outside diameter of my 1/4 W socket as far as possible, but it still wouldn't
> fit. I then used the flat side of my Dremel cutting wheel to grind down the
> ridge on the rod adjacent to the bolt head. This provided just enough
> clearance for my modified socket to fit over the bolt head. This did the
> trick and I don't believe I removed enough metal to cause any balance
> problems (I hope).
> Now does the new piston go in from the top or the bottom? I can envision the
> piston going in from the top and pushed down just far enough to allow the rod
> and wrist pin to be attached from the bottom. Now that I can get my socket on
> the pinch bolt, I could tighten it with an extension. Or should the rod and
> piston be assembled and then installed from the bottom the same way they came
> out? If done from the bottom, can you get a ring compressor in there past the
> crank? If not, can one compress the rings with ones hands?
> By the way, the shop manual seems adamant about the rods being assembled with
> the pinch bolts on the right hand side of the engine. Naturally the DPO had
> them in the other way. Should I turn all the connecting rods around the right
> way or leave them alone?
> Thanks for all the advise. You should see how badly the old piston is beat
> up. No matter how I get the new piston in, it's got to be a big improvement.
> Bob Donahue (Still stuck in the '50s)
> 52 MGTD - under DIY restoration NEMGTR #11470
> 71 MGB   - AMGBA #96-12029, NAMGBR #7-3336

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