Sleeving a David Brown engine - what to do with the sealing

joestewart · Dec 6, 2016

Gentlemen, I am in need of some advice. I am rebuilding a 1980 David Brown 990 and the block I am using is a solid block (no sleeves). This block came from a tractor that was sitting out in the woods for several years. The motor was filled with water and all four bores were rusted. I had to pound the pistons out. I brought the block to the machinist to have it bored to eliminate the rust pits. The machinist called me and told me that one of the bores has a crack and he will have to install a sleeve. I bought some "straight sleeves" and gave them to him, but he is confused about what to do about that "sealing ring" at the top of the bore. For those of you unfamiliar David Brown blocks in this model, there is a steel ring at the top of each bore. The ring projects a few thousandths of an inch above the deck surface to aid in sealing the combustion chamber.

Question: When you install a sleeve into a motor of this type, what do you do with the sealing ring? Is a "straight sleeve" appropriate for this set up? Or is there a different style sleeve I should be using?

Thank you in advance for your input.

Thad · Dec 6, 2016

That block is from a older tractor and not what the later models used. I have never tried to bore one of the early blocks.

RGMartin · Dec 6, 2016

(quoted from post at 21:09:25 12/06/16) That block is from a older tractor and not what the later models used. I have never tried to bore one of the early blocks.

Thad, if I am understanding Joe correctly, even the 94 series blocks have that insert ring in them. I have had them come out by accident when the shop bores through them.

The shop I used has just bored through them and dropped in the sleeve. Personally, I'd try to find a better block rather than use a repair sleeve in a questionable one.

If the engine was that bad, how much water was in the transmission? How rusty are the gears and hydraulics?

RGMartin · Dec 6, 2016

In addition joe, those steel rings have been flush with the top of the block on every one I have ever had apart.

My understanding of them from a DB engineer is that they were a space filler from when the block was carried forward from the 3 5/8" dry sleeve engine.

joestewart · Dec 6, 2016

Rich, thanks for the helpful responses. OK, I have a couple of questions:

1. The machinist bored right through the sealing ring and then pressed in the sleeve? How far past the sealing ring did he press the sleeve? A few thousandths past it? My machinist seems to think that these "straight sleeves" can't be used for this application. I found the following thread on the other forum, but it does not give any detail: http://www.dbtc.co.uk/index.php?name=PNphpBB2&file=viewtopic&p=7204460

2. If the machinist bores right through the sealing ring, there may not be much sealing ring left! I think these liners are 1/8 inch thick, and the sealing ring isn't very much thicker than that. Did this ever present a problem?

Regarding the rest of the tractor: Its junk. And it was 70% cannabilized anyway. I only used the block, and I put the rest of the tractor out in the iron pile. This motor is going on another one of my tractors that "threw a rod".

Thanks again.

RGMartin · Dec 6, 2016

I'm not an engine machinist, just spend money and time there.

What would the machinist do if it was a Ford block? Lots of them get repair sleeves added because of cavitation? I can't see how this is much different.

RGMartin · Dec 7, 2016

Another crazy thought, pop out the ring, and have the shop make you a flanged sleeve that uses the recess at the top? I don't know of anyone having done it, but don't see why it couldn't be done.

Downside of all of this is dollars. A good used block that only needs bored starts to look cheap.

Sleeving a David Brown engine - what to do with the sealing

joestewart

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joestewart

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