Classic Mini Engine Rebuild

[Minidave]

Watch this spot for details, coming soon!

[Counterfit_Mini]

Watching

[Minidave]

Step 1 is to get it mounted on my engine stand so I can turn it upside down to work on the crank and bearings later. Bottom end looks pretty clean, but I won't know what kind of condition it's in till I disassemble it and start mic'ing things out.

[davester]

Sorry Dave, but whose engine is this and what is it out of? But it is fun watching...

[Minidave]

I don't know what it's out of for sure, it's a classic Mini 998 engine, I can tell you that much. It belongs to my friend down in Steelvile and it's going into his Moke that we worked on while we were down there last week.

Here's the link to that thread, although I have more pics and vids to upload to it yet....

viewtopic.php?f=8&t=2948&p=27374&hilit= ... run#p27374

[Minidave]

So today was the day, I got the little engine that could all torn down, still have to go thru and mic everything but a few things were painfully obvious......first of all, I knew someone had worked on it because of the blue RTV all over it, I could also see the tabs on the con rods and mains had been bent over more than once - you're supposed to replace them.....and the head studs all (but one) came out with just my fingers.

I pulled the head off first, it looks like it's in really good shape, although there was the normal wear on the ends of the rocker arms and bottoms of the lifters. The cam looks great, tho the cam bearings look knackered - I'll have to do some careful measuring and make sure the lobes aren't worn and the bearing surfaces look correct. It definitely hasn't had hardened seats put in, that will have to happen for it to live on unleaded gas.

Then I turned it over to take a look at the crank end of things. Before I did I took a close look at the cylinder bores, there was no ridge worn at the top, but you could see the hone marks in the bores, and they were not done correctly - the cross hatching should be at about a 45* angle, this is more like 15* or less.

I took all the rod caps loose and pushed the pistons out of the bores, marking everything as I went along. The rods show evidence of someone taking material off (I suppose to balance the assy) but it's so crudely done it makes me wonder - it's not the kind of job I've ever seen out of a professional shop. Everything was looking OK till I got to con rod #4..........oh my. You can see the copper backing material showing thru the grey bearing metal - not a good sign. I also saw where bits of the bearing had melted onto the crank journal - it may be saveable, but I don't know if we should fix this one or the one that actually came from the car. I'll talk it over with the owner before we go much further. tomorrow I'll mic everything and see whether the crank's been turned undersize or the cylinders have been bored oversize already, then we'll know more.

[Minidave]

Well, I mic'd everything out and found someinteresting things.....

Cylinders are standard bore so no issue there, but the last person that worked on it did not check the ring end gap, and that put huge gouges into the #1 cylinder. We can bore it out, but if it doesn't clean up at the largest overbore size, we'll have to sleeve it.

I also found the crank has been ground, it's already 40 under on the mains and 30 under on the rods, those are pretty far down, it might not be feasible to take it any further. At that point the choices are to weld it up and machine it back to standard or replace the crank.

this motor can be saved, it's just going to take a little extra work and of course $$$$$$$.....

I'm going to visit a couple of machine shops on Monday and see what they think the costs will come to, then he can make some decisions.

[Minidave]

Spent some time down at the ol machine shop today, and as expected, everything is fixable with a suitable application of funds. Actually, the numbers we were discussing were not bad.

I sent the info off to the owner in an email and we'll see what he wants to do.

One thing I did figure out, I know how cylinder #1 got damaged. In the attached pic you can see (barely) that they didn't put the circlips back in the pin bush, the pin is a free floating design and with no retainer it could just slide out of the pin boss till it rubbed against the cylinder walls. Just bad mechanican'.....

[Minidave]

Well, turns out we're not going to overhaul this one, the owner found a deal on a good used motor so he's going to go that way.

[ragtopday Johnna]

I'm thinking you should hold on to this engine, Dave. We've got an old Italian bumper car that needs some go...

[Minidave]

Well, unfortunately it doesn't belong to me, although he might sell it. But considering how much money it would take to put it right, I'm not sure it's the right way to go on the bumper car. Actually, John and I were talking about making the b-car electric. Failing that a scooter engine/trans would be a simple and relatively inexpensive way to make it motor.

[gasmini03]

Dave,
Now that you have that one taken apart do you have a picture of what the rod bearings looks like so I might have some idea of what I'm up against?
Do you think your shop day could handle an engine swap?

[Minidave]

I'm not too sure what you're asking me, Gasmini......there is a pic of the rod bearings on this engine above in my 3rd post....I'm not sure what your rod bearing is going to look like, but just from the sound of it and the description you gave me (in the car) of what it did, I think you spun a bearing. If so you'll need to repair the crankshaft too, just like in this engine (however, this engine did not spin a bearing, it just wore one out - badly) If you look closely at the bearing in the rod #4 you can see that enough material has been melted and moved around the bearing shell that it's almost blocked the oil hole in the center of the rod, this bearing was just about to spin.

And if you tear it down that far you'd be silly not to re-ring it and do the valves etc.

I can swap a motor in one day, easily......depending on whether I'm changing out the trans from the engine or it's all together and it's a simple swap. And assuming there's no issues - mismatching parts or something.

If you pull your motor and bring it to me, I'll take it apart and tell you exactly where you're at .... but bring it all, carbs, exhaust, trans, starter, genset, radiator etc. Or just tow the car up and I'll take it from there......

[Counterfit_Mini]

If you do an engine swap I wouldn't mind seeing how it's done.