After finding out my my piston compression was low, I finally decided to make my 250 into a 300. Well, I know it’s not really a 300,
more like a 280, but it’s something I’ve wanted to do for a long time. For me the best thing of doing that was I did the work myself.
Sure, it cost a lot in parts, about 26,000 NT, but that because I went and bought everything new that was related to the job. I could
have re-used some parts, but the ones I could have re-used were cheap parts, why not buy new ones? Considering this is my first
engine rebuild, I was really surprised to have it run again for the first time today.
A few surprising revelations in rebuilding the motor. Damn, getting that piston into the cylinder was really hard. You have to put
the piston onto the piston rod, and then slide the cylinder onto the piston. The problem, can’t use a piston ring compressor sleeve
to help do that. Well, maybe you could, if you can actually find one. Took me 4 hours the first time, and I say the first time because
I ended up having to do it again. The first 2 rings are easy, it’s the oil ring that’s the real biatch. The cylinder at the bottom beveled
to allow the rings to go in easier. That works well for the first 2 rings, but the oil ring is different. The oil ring is really made of 3 rings,
2 really thin rings, and one wavy ring. The 2 thin rings go on either side of the wavy ring. Anyways, it’s that last thin oil ring that
can really get in your way of getting the piston into the cylinder. Instead of going in smoothly, it would buckle out of it’s position
and wouldn’t go into the cylinder. Ended up using an e-xato like knife to help me put pressure on the ring as I wiggle the cylinder
on the piston. During those 4 hours, I thought why don’t I just put the piston itself into the cylinder, then put the piston pin in
and connect it to the piston rod and put the piston clip in? That doesn’t work because the last damn oil ring will slip out of the
cylinder when you have to put in the piston pin. I also found out after talking to a mechanic friend of mine it’s much easier if you
move the cylinder side to side and not up and down. Probably has to do with the fact that the piston will move up and down and
not side to side.
Another revelation is that it's better to put in your coolant in first, if you have a water cooled engine, to check for leaks, than
put in your oil in first. I put my oil in first, then put in the coolant and began “burping” my coolant system for air as I was adding
coolant. After a few minutes of adding coolant and burping, I decided to take a look at my engine, and was shocked to see a
steady drip of coolant between my cylinder and crank case. Turns out that I put in my bolts that connect to the crank case
through the cylinder to the cylinder head in the wrong. There are 4 bolts, 2 are long and 2 are short. My friend suggested to
me I put the long bolts on the wrong side of the crank case. Even though I torqued the head down right, it didn’t apply the right
pressure, and so I had a coolant leak. Ended up having to drain the oil and replace the 2 gaskets for the crank case and cylinder
and cylinder and cylinder head, as I couldn’t be sure that they would work as they should. I guess the only positive thing for me
I can think about that is that I was able to teach my friend something, instead of always leaching information from him. Anyways,
since I never had read anything about what to put in first, oil or coolant, to a rebuilt engine, I just put in my oil and then coolant
and trusted that I had done everything right. I’m guessing that those of you who have way more experience in rebuilding
engines can get away with oil then coolant, but to me it isn’t practical. If you have a bad coolant leak, you’ll end up having to
drain the oil, and most likely not be able to re-use it.
Anyways, just thought I'd share that with you guys. Not sure if there are other 250 Grand Dink owners out there that want
to make their Dink into a 300, but if you do I can reply to this post with a complete parts list that you’ll need to do the job.