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TR2/3/3A Just rings?!

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HighAltitudeTR3

HighAltitudeTR3

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Hello friends, I have been playing with the idea of just replacing rings. My TR3 has good compression and the cylinders were in good shape, but I have some piston slap on my 4th cylinder. It goes away within a few minutes, but I don’t like it.

Open to thoughts and criticisms.

Thanks!!
 
Kinda depends on what you plan to do with the car, IMO. If you only drive in parades or on and off the trailer, then a little piston slap won't hurt anything.

OTOH if another 30,000 miles is a real possibility, and you have it that far apart; I would change pistons and probably liners.
 
I drive like a bat out of ****!! and I drive in the parade (might be done with that... it’s so tedious!) but I’d like to keep the car off the trailer... part of me is like fix what’s broken, the other part of me is saying put those 89’s in...

I would like to full rebuild but I am not set up for that. I can take on rings right now (in vitro). A full rebuild is 5 years down the road (engine willing)
 
You probably know this, but you can do liners with the engine in the car, too. It's a little more work, but not much. Just wrap some rags around the crank journals, so the crud from the water jacket can't find it's way into an oil passage.

I did much the same thing after getting my previous TR3A. It had broken rings in #3 and blew smoke, so I threw a new set of rings in it. Drove it almost every day for 5 or 6 years before I happened to get a set of 87s cheap and threw those in. Never did get around to a "full rebuild". In the meantime, I bought another TR3 just to get the overdrive, and since it's engine seemed healthier than mine, I swapped engines along with the OD gearbox.
 
I am kind of waiting for the big sale on the 89’s, but also the shop space. I have a TR4 engine in there and I’ve played with the idea of building up an engine to swap out, that would also be a viable option, but realistically if I could get away with just rings, which it sounds like you were able to, that’s would keep my driver a driver.
 
I did just the rings figuring that would be good enough until I could manage a rebuild. That was 1982.

In 2013 (about 50000 miles later) I finally got around to doing more with it, this time I did liners & pistons with the engine in situ. Pretty easy all things considered - by the time you pull the pistons to replace rings you have done most of the work needed to get the liners out.

You may want to read up on 89mm and see what cooling problems may be documented. I have no experience with those as I went with 87mm.
 
Replacing the rings will do nothing for piston slap. You could find a shop that will re-knurl the piston skirts...but good luck finding one to do that these days.
 
I agree with that IF it really is piston slap....
If it is then maybe the engine got too hot, pistons expanded and the skirts got scuffed on the cylinder walls. The slapping begins when the piston is cold and contracted.
 
If you change the rings, you really should hone the cylinders. Which may be harder to do with the engine in place than changing the liners....
 
I replaced just rings once, but my problem was the oil rings let oil up on the plugs. My guess is there could be more to your problem. It sounds like you have good compression and no big oil loss, so your valves are probably ok, and rings are probably good for a while, so you got that going for you. Because I am cheap and have time, I would leave the head on, pull the sparks plugs and would drop the pan to see what I could see. Perhaps you can look at the rod bearings or see up to look if there is a lot of damage to skirt on one piston and maybe even feel if the problem is a wrist pin or see if it is rod bearing. Then, depending on what I see, I would cut a new pan gasket put back together and ponder the money or pull the head and try something. If the problem seems to be all in one piston assembly, I might try and fix it somehow. Having said all that, the cheapest and best way might be some 87mm and leave the crank in and do the work with the motor in the car.
 
malbaby said:
IMHO...leave it or pull the engine and recondition it completely.
Click to expand...

Add a vote for that. I rarely disagree with advice on this board but if I’m messing with the liners it’s only when the engine is pulled and I’m doing a proper rebuild.
 
I agree with CJD, I don't think new rings will do a thing toward quieting down your little noise. If in your shoes I'd drive it another five years and reevaluate the noise.
 
Yes for sure doing a complete rebuild is the way to go. The last 2 motors I rebuild, I pulled the motor and refurbished, repaired, and painted every little piece. Anyways, doing a rebuild with short cuts created this disagreement between some friends of mine. One guy said that you cannot put new rod bearings on an older unpolished crankshaft even if the crankshaft looks good to the eye, and if you did the motor would start knocking in 10K miles. The other guy said he has replaced just rod bears many times and the motor went for a long time if they were not driven too hard. I actually respect the guy who said the motor would wear out quick because he is more of a profession in the area, but again he sells parts too. They did both agree that you could replace the rings and hone the cylinders, but the changing of the rod bearings was disputed. So, I am curious what the guys think here.
 
One of the Triumph manuals (not sure which one offhand, maybe Haynes?) actually recommends changing rod bearings every 30,000 miles, engine in the car, as preventative maintenance!

I've done it myself, several times. Sure, the result might not live as long as a properly rebuilt engine; but there's no way it dies in 10K miles unless you did something really wrong (or something unrelated happens).

First time I did that, it was on Dad's TR3A, back around 1974 (or maybe 73). Had to do it in the yard, with snow on the ground (my Chevy was on jackstands in the garage). Threw a tarp over the top and a heater underneath, to get things warm enough to handle with bare hands! That engine was still running fine, with no further internal attention, in 1998 when a wheel came off and dealt the final blow to the body. (It was a rust bucket even in 75.) I don't know how many miles it covered in that length of time, but it was likely close to 100,000. At the time it blew up, Dad was using it to commute to work (on a weekly basis) 150 miles each way. So he wanted it back on the road as quickly as possible, even if it only ran 6 months (the end of his contract).

He did mention that it didn't have as much punch afterwards, but I believe that's because I also changed the 4.10 rear end for a 3.70. I figured that running for hours with the tach needle laying on 5 grand had something to do with the swallowed valve. It's also possible that the ruined head had been shaved for more compression.
 
Hah! Found it! Page 34, paragraph 30 of the Haynes manual.

Sorry for the poor quality scan, not mine. I hope it's legible.

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