Pump Timing and Wet Stacking

My seemingly never ending David Brown 885 wet stacking problem. Finally got around to installing a hotter thermostat (for a Toyota application, I think), we'll see if that helps tomorrow. Meantime, the exhaust manifold is sooty inside but dry even though the manifold to muffler connection is dripping black slime and the muffler is very wet inside. As I was inspecting things before dropping the hood back on I noticed the block/fuel pump stake marks do not line up. The pump mark is misaligned with the block mark by a stake mark width. Viewed from above, the pump mark is clockwise of the block mark. Could this have any bearing on wet stacking?

Timing is slightly advanced which MIGHT help already. Most diesels that have wet stacking trouble are usually low on compression and if so no amount of pump/injector
repair will help. What will help is to work it to get the engine temp up to 180/200 degrees for awhile. Diesel exhaust temp is MUCH cooler than gas engines at idle/light
load use. Raising the static compression is what works best, but that requires major engine machine work to get the compression around 400 PSI. Any lower and engine will
be more likely to have light load wet stacking issues.

This started after an in frame w/pistons, rings, cylinders rigid honed, all new valves and exhaust valve seats. The old exhaust seats and valve faces were horribly rust damaged which accounted for why the thing wouldn't start hot or cold without starting fluid. Now it starts in mid-thirties with only 15 seconds of thermostart. The old thermostat looked like a cut-down Chevy thermostat marked 180. I put in a genuine DB/Case part numbered stat rated at 172 when it went together. The radiator was 3/4 clogged too, that was corrected. The engine used to run right at 200. With the "new" DB stat it runs at 170. The stat I put in today, a 180 runs the same temp as the 172 DB stat. I got my thermopen from the kitchen and stuck it in engine water outlet in the radiator, it read 160 so the gauge is off by ten degrees so the engine has been running at 160 for over a year. I may have found the problem.

I had the radiator cap off as the engine warmed after the stat was changed. When the tractor gauge read 180 water started to move indicating the stat was opening. The temp then dropped to 160 and that was it, the temp never rose to thermostat "open" temp after that. It is as though the radiator is doing too good of a job now that it's no longer half stopped up.

What are you using the tractor for? If you are not
pulling it very hard this is probably what you are going
to get. Keep it revved up to a 1000 rpm or so will help.
As far as your stake mark for the pump that is usually a
ballpark setting. Aligning the marks in the timing
window on the pump and setting the crank position to
the specified mark is how to check the actual pump
timing. Crank timing marks are aligned by coming up
on them in the proper direction of rotation. In other
words if you go too far do not just back it up that little
bit. Turn it back an inch or more and come up to the
mark alignment again and stop.

195F is good and 210F is better with a 15psi Rad
Cap and 50/50 coolant
Mix .00

What you are saying proves to me and I preach this all the time. Don't waste your time on trying to do a ring job and an in frame on
a worn out diesel. The rings will never seat properly and you will never get maximum compression. Bore it, Sleeve It and put new
pistons in it. I rebuild a lot of engines and I will not do an in frame under any condition.

(quoted from post at 05:08:57 03/30/23) What you are saying proves to me and I preach this all the time. Don't waste your time on trying to do a ring job and an in frame on
a worn out diesel. The rings will never seat properly and you will never get maximum compression. Bore it, Sleeve It and put new
pistons in it. I rebuild a lot of engines and I will not do an in frame under any condition.

Click to expand...

Not so much wore out as water down the exhaust (my guess) had ruined the exhaust valves and seats. As I received the tractor, the intake valves were at zero lash and the exhaust were per-loaded slightly. It'd start okay the first season but after that only with ether, which was likely why one top ring was broken. New pistons put the piston to wall back in David Brown specs. Ring gaps were on the tight end of spec. I agree with your opinion on in-framing. I wasn't my first choice. I'd replaced both clutches right after acquiring the tractor and replaced the brakes and fixed a suction side hydraulic leak. I had no stomach for splitting the thing again to remove the engine. We had a 27 morning a couple weeks ago and the tractor started right up with minimum per-heat. In the almost 200 hours since the in-frame the oil level has never been below the full mark.

I'm far from an expert but I've put my time in as well. I came up in an industrial and truck engine machine shop in the early eighties. Spent from 1988 to 2009 in NASCAR. Worked for two Cup teams and two car manufacturer race divisions doing engine development and qualifying engines (back when there was such a thing). Worked for two NHRA pro stock teams after that before spending a couple years in an automotive machine shop doing a combination of drag, boat and circle track engines before retiring in 2019. If you're a NASCAR fan you might get a kick out of this . . . The cylinder hone I used was loaned to me by Petty Enterprises.

(quoted from post at 01:34:10 03/30/23)
195F is good and 210F is better with a 15psi Rad
Cap and 50/50 coolant
Mix .00

Click to expand...

The dogs and I are about to head to town for another thermostat and lunch. Given there was no improvement with the 180 over the 172, I'm going straight to 210-212.

Don't know why but some engines
are hard to get warm. I used to
have a 81 f100 and the only way to
get it up to temperature was
blocking 3/4 of the radiator. It
stayed blocked winter and summer.
The 195 degree thermostat did
nothing for it. You may end up
having to block part of yours.

(quoted from post at 13:52:50 03/30/23) Don't know why but some engines
are hard to get warm. I used to
have a 81 f100 and the only way to
get it up to temperature was
blocking 3/4 of the radiator. It
stayed blocked winter and summer.
The 195 degree thermostat did
nothing for it. You may end up
having to block part of yours.

Click to expand...

I considered making velcro shutters, but knowing that it wasn't doing this when it ran so lousy it wouldn't start, well, I had to try before going that route. Removed yesterdays 180 thermostat replacing it with a 198 this afternoon. The 180 opened at 180 dropped to 160/170 and stayed there. The 198 just barely started to open a little past 180, seemed like it was full open at 190 then never moved. The muffler is a mess inside, the most unorthodox thing I could think of to try to dry it out to avoid buying a new one was to put it in the firebox of our wood fired boiler. So that is where it is. I considered pouring gasoline in it and striking a match. Got away with that when I was 18 burning out glasspacks. Figured I might ought to quit while I was ahead on that sort of thing. There is some plowing to be done tomorrow, fingers are crossed this works.

Relating to your Ford experience, bought my wife a Toyota Corolla in '91. That thing would freeze you half to death in winter, the temp gauge never came up off the peg. After changing thermostats a couple times I gave up and cut a piece cardboard that blocked half the radiator. Car got 40mpg and didn't get parked until 2018 when it had 485,000 on it and wouldn't stay in 5th. Sold to a co-worker for $100 who made it his mission in life to get the car to a half million miles. He used a bungee cord attached to the shifter to hold the tranny in fifth.

What about a set sleeve engine where you can pull and replace the sleeves with it in frame ?

No I will still not do one. What about Micing the crank and replacing the rear main seal. When you loosen the main caps to roll new main bearings in the weight of the crank will destroy the rear main seal and it will leak nearly every time. What about the plastic piston cooling jets in a Cummins falling down and getting broke while trying to roll the bearings out. Sorry I don't do in frames. If I rebuild one it comes out and goes on the engine stand. I don't like come backs.

(quoted from post at 05:13:41 03/31/23) No I will still not do one. What about Micing the crank and replacing the rear main seal. When you loosen the main caps to roll new main bearings in the weight of the crank will destroy the rear main seal and it will leak nearly every time. What about the plastic piston cooling jets in a Cummins falling down and getting broke while trying to roll the bearings out. Sorry I don't do in frames. If I rebuild one it comes out and goes on the engine stand. I don't like come backs.

Click to expand...

Macks and Detroits were the worst about the main bore shrinking in use then burning up and spinning bearings after rolling in a new set of bearings. Sleeved damaged main bores and fit new caps on a bunch of both.

You don't have to do a thing to a Detroit to make it leak.

The 198f thermostat has the engine running in 200f range according to the gauge. Ran the tractor for around three hours pulling a rotary mower in variable grasses. After two hours (with hood off) there was a small dribble of the dreaded black slime making its way from between the muffler inlet and the exhaust manifold adapter. I think it is residual from inside the muffler. Running another hour the same dribble appeared. Today I'm going to install a temporary two foot straight exhaust stack and cross my fingers the wet stack problem has been resolved and the exhaust stays dry.

One thing of note - of the three thermostats tried, one saw the temp rise to the opening point but then drop back ten or more degrees and stay there. Evidently it is sticking, something to watch out for in these days of price point before quality.

I'm bumping this up for anyone interested. My query as to pump timing causing wet stacking was answered as, probably not. So I went on a quest to raising the water temperature. The only listed thermostat for my tractor was 172. The one I removed due to a fitment issue when the engine was in-framed was a 180. It only worked (dry exhaust) likely due to the radiator being clogged. Before being rodded out during the in-frame it was a constant struggle to keep the water temp below 200 if working the tractor to any degree.

Fast forward - after three attempts I ended up with a 192 thermostat that required slight trimming of the O.D. to make it fit while still leaving the embossed ring that seals water from passing around the O.D. The first two thermostats tried would not hold temp to their stated opening temperature. Once they opened, the water temp dropped and never recovered. Since the 192 thermostat has been installed it has taken seemingly forever for the muffler to "dry out". Currently, the black mess seeping from between the mufflers connection to the exhaust manifold has stopped - and from the exhaust manifold exit to the weather cap is finally bone dry.

This post was edited by ScottNC on 06/10/2023 at 06:34 am.