Rebuild 225 or replace (225 or 231?)

First post here...

My project is a restomod of my grandpas 43 MB. He owned it for over 30 years. Putting the 43 MB tub on a 71 CJ5 frame. The MB frame was pretty rotted and more than I could fix. I sold it to someone who restores MBs and GPWs so it went to a good home.

The 71 CJ5 frame I bought came with a 225, T18/D18 combo with a 30 spline D44 rear.

The 225 engine would not turn over a full revolution and after pulling the heads off I found thick rust buildup on one cylinder keeping the piston from moving up. I've called a few machine shops and gotten quotes for a full rebuild from $1,200 to $2,000. Is it a waste of money to rebuild that? Should I look for a used 231 that will drop right in? The benefit I do see to the rebuild is of course I'll have a fresh engine that will last a long time whereas a used engine is more of a gamble. I don't have an unlimited budget on this project, looking to save money where I can when it makes sense.

Thanks for any input!

 

A few more pictures.

 

Looking at those cylinder walls and heads that looks like a complete rebuild.........more than likely you'll have to bore it , new pistons & rings, grind the crank , recon the rods, new bearings, grind the valves, may have to surface the heads , block or both , new oil pump and timing chain, maybe new lifters and perhaps rebuilding the rockers also , camshaft would also need to be checked and a gasket set........not sure all that can be done for $1200 ............get it in writing......and check your size crank size before you go very far if it's already undersized that may change your mind on direction............where do you live? Sometimes these motors come up 4-sale that are already rebuilt.

 

Atlanta.

What's the typical price for one of these engines already rebuilt? Any cheaper than having the work done on mine?

 

I'm just saying they do come up from time to time that someone already rebuilt...............you will not know what you have and it's cost to rebuild , until it's taken apart and properly inspected & measured.

 

The cheapest route is always a different used engine, although there are obvious risks.

I would probably try to patch it up and see how it runs - I'd disassemble, hit the cylinders with a ball hone, and then decide. If you end up boring the cylinders, a factory short block will be close to the same cost as having the machine work done and buying new pistons. New pistons will be the costliest item in your parts list. But I trust my work more than the work of an anonymous laborer in Monterey, so I'd probably do it myself.

 

In short, there is no replacement for the 225.. Build it..

 

I love the 225,

 

I like mine and am going to fix a bad piston and run it until I break it again. Plenty of power, light, interesting too. Fun to tinker with and just weird enough to still source parts for, but have people scratch their heads about.

 

rebuilt engine in mine . 1983 , now has 92881 miles(engine) on it and still running strong . I vote rebuild what you have

 

Another vote to rebuild here.
The 225 is a nice little motor.
Mines runs strong but will do the rebuild when the time comes.

And welcome Phil will , what part of Atlanta are you in? I'm down in the peaceful town of Riverdale

 

Welcome philwill and I too love the little 225 Dauntless.

 

Sounds like the consensus is a rebuild. Better start saving my pennies! I'm only doing this once so I want to do it right. I like the idea of having the original Dauntless in it and not some random used 4.3.

alpina72 I'm an hour north of Atl up in the sticks in Woodstock. No neighbors to bother with loud exhaust

Thanks for the input everyone! Here's a rough mockup of how it sits now. Don't worry, the hood cowl has been removed. It was to fit an F-134.

 

I like it . that's a plus . inside storage while you work

 

Mine looked worse. I rebuilt it and am glad I did.

 

Anyway, the 4.3 is not a drop-in replacement for the 225. If you found a 231 - even or odd fire - that would go in without any big changes, but not a 4.3.

Do you know why this Jeep was parked so long ago?

What I was suggesting was doing only what needs to be done to get the engine running. Clean up the cylinder walls and put it together with some new gaskets and see what you have. Or clean the bores, put it together with the old head gaskets, crank it and test the compression. The heads don't look terrible, and you can't see the cylinders condition due to the scale on the cylinders. Snoop around, and if you don't see any catastrophic problems, just clean up the effects of the water and see what you have.

 

No history on this engine.

All six cylinders have a noticeable ridge at the top enough to catch a fingernail on. From what I've read that usually indicates an overbore is required. Do you guys think I could ream it out at home or is that risky messing up the cylinders?

In the meantime timgr I'll try to clean it up and put it back together as is and see what my compression is like. Should be able to do that over winter break when college classes get out.

Noticed a 231 reman long block for $700 on eBay. Would my 225 intake manifold work on a 231? Most of the other long blocks go for around $1,800 which I'm thinking would make it cheaper to rebuild mine. Decisions, decisions...

 

You can get a notion of what the taper using a compression ring. Measure and compare the gap in the squared-up ring at the top and the bottom of the bore.

 

Not trying to discourage your attempts to save this motor , But as I mentioned above I think your into a complete rebuild.......Water / Moisture that has rusted rings to cylinder walls will usually have a negative effect on that surface. Meaning the cylinder walls will usually be pitted or damaged beyond the use of any hone. Sometimes even boring the cylinder may not be enough to clean it up to the point of getting the new rings to seal.

At this point with all of the garbage, rust , carbon in there just trying to turn it over to get the rods unbolted and get the pistons to exit.........further damage will occur to the cylinder walls and Pistons. Likewise the ridge you mentioned at the top of each cylinder may very well prevent the piston from exiting without breaking a ring land on the way out.........if you have or can find and old cylinder ridge reamer to cut that lip off that would be wise at this point to try and preserve anything that still may be able to be reused.

If your old manifold was made as a 225/231 intake your probably OK as the later 231's had taller ports..................take it slow as you disassemble that motor.