knocking 225 in my CJ3a

So my v6 has a knock on start up again(I replaced the main bearings a couple years for the same issue) I got a quote from the local auto repair place to rebuild the motor and after he told me 4k as a rough quote I quickly left and need to come up with other ideas.

I was thinking now maybe a good time for a sm420 and rebuild the D18 while its all apart. I currently have no place to rebuild the motor myself so solutions need to be modular as in find a motor, remove and replace ect..

What you would guys do?

TIA
Kevin

 

4K is way out of line unless you are looking for 350 hp out of the 225 (very possible). I may know where a 231 is at that had a carb issue but was otherwise solid as far as I know. I can check on it if interested. PM me. The engine is/was between Canby and Oregon City. Your flywheel would need to be re-balanced to match the even fire motor. I'd check out some other places as well. PERS (Portland Engine Rebuilder's,(Where I have much of my machine work done that I don't have the equipment to do)) or talk to Steve at NAPA Machine in Canby. There are other options locally too. Paola's engine rebuilding in Oregon City has been around forever , Butch Stetson if going for performance but takes a while, Archie Sommer's in Vancouver, etc.

 

Could be several things. Buick main tolerances are exceptionally tight and if it is put together by the best Chevy engine guy in the County, its likely not tight enough for oil pressure (Chevy's are very forgiving). I also would highly suspect your tolerance on the oil housing cover to the pump gears is also not tight enough which leads to lower oil pressure and possibly starving a bearing. Find a Buick or Pontiac engine guy and he will go through it for about $2500.

 

Guess I should have started at the basics. Have you checked oil pressure on start up and when warm? May give a lot of info.

 

Kevin,
How old is your 225? Have you got good oil in her? The oil pump may just weak other wise. I would try the pump before a rebuild.

 

Would not the knock usually indicate either a piston pin or rod bearing clearence problem? My experience is usually by the time you can hear the knock, the problem will not go away with a new oil pump-damage has already been done. If it is a rod bearing, you can likely replace it without pulling the motor if the crank is still good. Nickmil's suggestion on the hot/cold oil pressure is a good one because if a bearing is really hammered, you will have minimal pressure in both cases. If the pressure is good when up to temp, it is likely a piston pin.

 

A little more history on the motor. a couple years ago in the mornings you could hear it knock until oil pressure built up to 5-10psi. after it was warm it would average about 10-15psi at speed and was quiet and ran good at idle but oil pressure was around 5psi. So I went and got some help and after working on it a a bit checking things we replaced the mains. After this no knock and oil pressure was 40-45 after being warmed up and at speed. Fast forward to now oil pressure is around 35-40psi when warm and at speed, idles great no other noises and plenty pf power. This motor goes though maybe a quart of oil between oil changes and believe most of that leaks out the real main seal.
I'm thinking of calling some of the rebuilder's in the list above and get more ideas.

If rebuilt just looking for just a torque motor nothing fancy. it is plenty fast for how I use it.

 

Did you inspect/measure (Plastigage) the rods when you went after the mains?

Usually it's the rods that go first, before the mains.

Check with local machine shops on rebuild or exchange of your engine. You could buy a short block or long block engine and do most of the grunt work yourself. If you want something extra like a specific cam, you can request that at the time you order.