I determined that my engine's problem was not a thrown rod as I initially thought, but a cracked #4 piston. All of the other pistons look surprisingly good. Would it be possible to replace this piston, which is the one nearest the firewall) without pulling the engine by pulling the head, dropping the oil pan, unbolting the con rod, and pushing the piston up? If this is feasible, it would seem that this job would take only 5 hr. or so of time and would avoid many of the complications of pulling the entire engine (discharging the A/C, disconnecting fuel and wiring, etc).


Anyone know a source for single pistons? I don't think that I could replace all 4 by dropping the pan; only the rearmost two.


Thanks,
Drew

I have the bits and pieces, some large, of a B23 engine that threw a rod. The good pistons, connected to their con rods, were - I suppose - OK.

Let me know if you have an interest.

Bob

:>)

B.C.,

I wonder how common this phenomenon is - B23 motors throwing rods. There are at least a couple of threads on this subject in the archives, and yet the B23 is regarded by many as the "bullet-proof" OHC redblock.

Charles

This is some what related. My son ran his 87 240 at little dry so we ended up replacing all the main and rod bearings. Well, he also ground down the bottom cup or keeper for the rear most main beaing, I think it might be called the thrust bearing. So I took it to a welder and had him weld a bead on each side of this item ---then I ground it down to just fit and it took out the slop very nicely. The reason I even mentioned it was because of the weight factor--I'm almost certain that I increased the weight in that area but it didn't seem to cause any vibration if we stayed under 2500 to 2800 rpm and we lived with it til we sold it for $5oo

To get the pan off around the oil pump you will have to lower the crossmember and support the engine. All of the rods are accessible after that.
A used rod and piston assembly, or just a used piston is the way to go. Once the head is off you will see if you have a dished piston or a flat-top - just be sure to get a similar one.

Isn't it critical to get not just a "similar" one, but one that is a match in terms of its weight? Otherwise, wouldn't there be a serious vibration?

Given that there are different brands of replacement pistons, I can't imagine that they're all a match for weight.

Or am I being too critical? I've never had to do any work on such internal parts since I started owning Volvos back in the '70's, but before that, in the '60's when I was in H.S. and college I did a lot of engine rebuilding, and even a little of (what they call today) "tuning" for a English Ford Cortina set up for rallying and autocrossing. Anyway, we were always careful to rebuild with "matched" sets of pistons, etc. I can't imagine that it's different today.

Regards,

You are correct, if one was going to use an aftermarket piston. If one stays with the Mahle or KS original part, then the weights are so close as to not matter. That is why I advise installing a used piston from a similar engine. Those German parts are quite accurately made.
Of course Volvo engines have never been noted for smoothness in the first place, and many other components contribute to the buzziness of them. That's one reason why the aluminum power steering pump brackets snap in half all the time. Hondas and Toyotas don't have those kinds of problems.

Hondas and Toyotas don't have those kinds of problems.


Hondas and Toyotas have other kinds of problems, like rust that's worse than Volvos of the same year and engines that eat themselves if the timing belt breaks ;-P To give Honda some credit, they do make some nice medium-sized motorcycles, and I've seen quite a few Civics/CRXen with over 300k miles on the clock (but rusty).


If I were getting another car that wasn't a Volvo, I'd have to go for a Subaru Legacy 2.5 manual. Very reliable/durable, extremely smooth engine, and a 50/50 AWD system that doesn't torque steer like crazy and puts power to the rear wheels all of the time, unlike new Volvos that power the rear wheels only when grip is lost. Plus the interiors are simple and gimmick-free and some of the engineering touches like equal-length half shafts and the "hill holder" are great. I'd miss the huge load area and tiny turning circle of the 240, but the Subaru is as close to an ideal car that's still made and sold in the US today.


Either that or a Honda CRX HF, which, despite being FWD handles amazingly, makes 50 mpg highway, and has a huge rear load area for a car that size.


-b.

Here is a source ... but OUCH it ain't cheap....
Swedish parts
--
Happy Motoring! 86' 244 "Grey Mare" '87 245 "Grasshopper"

suggestion: budget more than five hours for this job.
you could advertise in the classieds here and check volvo parts sellers on ebay to find someone with a piston.

What you are asking is entirely doable. Just make sure that you get the correct used piston, A, B, C, D etc. Are you going to reuse the existing rings or are you going to run new ones. Part of cross hatching the cylinder walls is to aid in breaking in the rings and some folks will tell you that it is absolutely critical. Back in the day when people were frying their turbos cars all the time we had a guy that would come out and bore and hone a cylinder for you right there in the car. If you had a hole where there was metal transfer he would machine it up right then and there it the dealership parking lot, cool deal indeed. I imagine if you could transfer the rings without damaging them then you could run the old ones but you run the risk of stressing one of them and having it break down the road. Your other option is to stuff new rings in it on the old cross hatch or buy a hone and hone it yourself. I have done this before too and had it turn out ok, but it is alot of work as well. The last car that I did something like this on blew it's head gasket so hard that it hydraulicked one cylinder and bent a rod. I bought a #3 rod from the bone yard, stuffed it in just like you are thinking with that piston and it has worked choice for the past 6 years.

Good luck,
Mark