Author Topic: SR-1 governor mystery  (Read 561 times)

pinecone9

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SR-1 governor mystery
« on: September 22, 2019, 09:54:49 PM »
Hello, all!    I have a SR-1 that I purchased new back in the 1970s.   It's been overhauled twice,
most recently about 1  year ago.    I do all the other maintenance and repairs.   I'm hoping that
someone here has seen the following symptom:

The governor has stopped working.   The engine doesn't overspeed, but the speed wanders
and RPMs decrease with load.   Onset of problem was gradual.  Engine starts and stops just fine.
Fuel supply is fine, air intake is  unrestricted and exhaust is unrestricted.

With the engine stopped, I removed the access door to the fuel injector pump.  WIth the control
manually set to the RUN position, the mark on the rack lines up with the right edge of the fuel
injector.   Using a screwdriver to gently slide the rack to the right, it seems to move freely and
I can feel the tension of at least one spring.

I am able to measure the engine speed because this engine is part of a Kohler generator set, and I
have a vibrating-reed frequency meter on the AC output.  I am not using the engine except for
very light loads until it's fixed.  We have a solar power system, but this generator is our main source
of AC power for household use and the well pump during the winter months.

The engine itself has been highly reliable (unlike the electro-mechanical stuff made by Kohler).   
However, the remote start -- which replaces the start-run-stop handle with a mechanism--seems
to be working.  I'm posing in this engine forum because it seems to be an engine problem, not
a control system problem.

Any ideas or suggestions, anyone?   Thanks!

oldgoat

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Re: SR-1 governor mystery
« Reply #1 on: September 23, 2019, 11:19:07 AM »
Pull the front cover off where the starting handle goes . The governor is right in front of you. Check for worn pins in the governor linkage check you haven't lost one weight or broken a spring. Check that the speeder spring which is attached to the governor rack and the cover is still intact.

ajaffa1

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Re: SR-1 governor mystery
« Reply #2 on: September 23, 2019, 12:28:27 PM »
Hi Pinecone9, welcome to the forum. A most interesting problem you have there. As Old goat has already suggested, you need to pull the cover of the governor assembly. Once that is done you should see something very similar to the photos below. These are photos of a Lister ST, but there should be very little difference between these and your earlier model Lister SR.

I suspect that you have wear in the governor linkages causing the blind spot between the demand for more/less fuel from the injector pump. If you look at the photos, you will see that there is a piston in the middle of the governor assembly that pushes against the governor linkage. If these are worn there could be a small gap between them when running, causing the poor governor control.

If you look at the photos you will see the governor linkage has a brass fulcrum, this would have been originally set at 1/2" from the face of the crankcase, it has a lock nut on it, undo this lock nut. Remove the split pin that keeps the governor arm in place and slide it out of the way, now rotate the brass governor fulcrum by one half turn clockwise (180 degrees). Refit the governor arm and center it on the governor piston now tighten up the lock nut. This should remove the backlash you have in your governor linkage. You may need to adjust your RPM after.

Bob

pinecone9

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Re: SR-1 governor mystery
« Reply #3 on: September 27, 2019, 05:27:33 AM »
Thanks, oldgoat and ajaffa1. That's all super helpful--especially
the great photos!

On this engine, the front cover is attached to the speeder spring
by the speed adjusting screw.   The threaded end of the screw
emerges the from a threaded bushing screwed into the door.

Do I need to first remove the fuel pump housing door in order to
unhook the other end of the speeder spring from the governor link,
before removing the front cover?   Or is there some other trick?

Here's what I tried:

First, i measured the protruding portion of the screw, so I'd have
some way of re-setting the speed roughly correct.

Then, I tried unscrewing the bushing from the front cover, cleaning up
the threads on the adjuster screw, and trying to run it back though
the  bushing.  But it only moved about two turns.   The problem is
that the external threads are beat up and there is nothing to grab
to apply torque --- the entire accessible portion of the screw is
threaded.

I tried running two nuts onto the the end of the screw and jamming
them together.  But I'm afraid to turn any harder for fear I'll shear
the screw (it's only #10 x 32 -- I think).  So I sprayed the nut/bushing 
with penetrating oil (PB Blaster)  and I'm going to let it sit overnight.  .

I've adjusted the governor speed in the past, but only by less
than one turn.  It seems possible that no one has taken the screw
all the way out since the engine was manufactured.   The fuel
pump door isn't too accessible in this installation, so I sure hope
I don't need to remove it.

Sorry to ask such boring questions..  I'm sure it will get more interesting
once I get the cover off.

oldgoat

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Re: SR-1 governor mystery
« Reply #4 on: September 27, 2019, 01:24:25 PM »
Taking the fuel pump cover off is probably the easiest way in your circumstances to un hook the spring. All the listers I have come across have a slot in the end of that screw. Don't know if this is standard or an owner modification. The steel screw has probably seized in the alloy cover and it will be easier to free it up with the cover off.
Oh the joy of old motors but just think of the satisfaction when it is all working well.

ajaffa1

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Re: SR-1 governor mystery
« Reply #5 on: September 27, 2019, 02:17:48 PM »
Hi Pinecone9, I`m with Oldgoat all the way on this one, remove the injector pump cover and disconnect the spring using a pair of long nosed pliers. This will allow you to remove the governor assembly cover without damaging the adjustment screw or spring.

Once you have access to the screw wind it anti clockwise as far as it will go, now hit the rusted thread on the outside of the cover with a rotary wire brush in a drill or angle grinder, this should free it up allowing you to remove it if you desire. If you do strip the thread in the aluminium housing do not panic we know how to fix that problem with a Helicoil or threaded brass insert.

Yes it should have a screw driver slot in the end allowing for adjustment and also providing a way to hold it in place while tightening the locking nut.

Bob

pinecone9

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Re: SR-1 governor mystery
« Reply #6 on: October 03, 2019, 11:25:20 AM »
After a spell of bad weather, I'm finally back working on the SR-1.   Then it took me a while
to get the fuel filter and the solenoids housing detached from the front cover.

That was a  good call on unhooking the spring.  Once I had the cover off and got access to
the head of the screw, unscrewing it was no problem.   Oddly, an ordinary 10-32 nut would run
over the screw just fine.  Apparently the bass bushing has much tighter  tolerances--I suppose
to prevent oil from leaking out.  I cleaned up the the threads on the screw with a die,and now
it turns easily, so it should be easier to remove next time.

Now the bad news:  nothing looks obviously wrong.  It's difficult to measure the play in the
entire linkage, from weights to rack.  But the most play seems to be in the joint where he
rack meets the lever, perhaps around 0.2 mm.   I'll try to get a more accurate measurment
tomorrow.

If correct, that means at most 0.2 mm of wear--and probably a lot less, since it can't have fit
perfectly when new.   The linkage is  kept under tension by the speeder spring and should
never go slack, so shortening due to wear is more of  worry than play.

There is no noticable wear on the pivot or lever arc, but a lot of side-to-side travel.  However,
it appears to have been designed that way: the pivot shaft is held in place by a C-clip on either
end, each with a flat washer, and that leaves it free to slide about an 1/8" inch.  Perhaps that's
to spread out the wear on the lower end, where it meets the governor sleeve.

Also, with the rack set with the calbiration mark to the right of the fuel injector pump (full
mark exposed), and the govenor sleeve flush with the lever end, distance 'M' appears to
be correct (1/2 inch) if I understand the diagram on p. 27 and the text on p. 28 correctly
(of the Lister *Instruction Book for Air-Cooled DIesel Engines* (1970).

The calibration procedure on page 28 calls for a feeler gauge (0.015 / 0.017 inch for the
SR-1).to be inserted  between the at point 'G' between the start-stop control lever and the
"run" position control  lever stop.  With this shim in place, it says to loosen screw 'H'
and turn the control lever locating plate it until the calibration mark on the rack lines up with
the right edge of the fuel pump.

Q1: Am I correct in thinking this is setting the leftmost rack travel, and that this corresponds to
the maximum fuel volume per injection?

Q2: Also, if wear has shortened the governor linkage, shouldn't that increase the maximum leftward
rack travel (and thus maximum acceleration)?  The governor weights excert force that moves the
rack to the right, decreasing fuel volume.   But the symptom I'm seeing is too little governor feedback,
not too much (oscillation).

Q3: is it possible the governor isn't the problem, but the fuel injector pump or even the fuel
injector?  (Both are new as of the rebuild 1 year ago.)

Unfortuantely, this engine is remove-start so it doesn't  have a plate with stops--nor is there
any obvious place to insert a shim.    Guess I'll have to go by the distance onthe rack, which
Lister kindly provides: 0.046 / 0.052 inch.for the SR-1.  (There's a typo: it says "0.46 / 0.052" 
but the minimum can't be larger than the maximum.   Fortunately, it also gives the same
tolerance in metric: 1.17 / 1.32 mm--which agrees with my correction to the text..)

With clothes pins on the rack, I was able to get a ballpark number of less than 2 mm of travel.
Tomorrow I'll try to get a more accurate measurement.   The tolerances on rack movement
appear to be very stringent: 0.052 - 0.046 =  6 thou.    The manual warns that the "maximum
must not be exceeded."

I count 5 joints, all steel-on-steel, in the linkage between the governor weights and the rack
(plus one cotter pin).   The joint at the top of the lever is a bent rod stuck in a hole in
the lever, with dubious alignment.  Even assuming the splash lubrication is adequate, I'm
scratching my head, wondering how it lasted this long. :-)

Q4:  How often have folks here had to adjust control lever locating plate on their SR-1 engines?
Once a year?  Once a decade?

Sorry to ask so many questions, but I haven't solved the mystery (and may on the wrong track),
so any clues would be  much appreciated.  Thanks!

pinecone9

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Mystery solved!
« Reply #7 on: October 04, 2019, 02:46:33 AM »
Hold the presses!   While trying to take measurements of rack movment,  I dropped
a clothespin in the bottom of the housing.  Reaching down to pick it up, I discovered
(purely by accident) that the bolt on the hold-down clamp for the fuel injector pump
is loose!    Of all the gal darn things...

I've never had the fuel injector pump out, so it must not have been properly torqued
during the last rebuild.   The engine ran fine until the bolt came loose.   AFter that,
 I'm amazed  it ran  at all.  *No wonder*  the governor couldn't control the speed. 
And it must have thrown  the timing way off.

So tomorrow I'll stick put it back together (unless someone here suggests something
else I should check or adjust while I've got the front cover off.).

Thanks ajaffa1 and oldgoat for your good help with the speeder screw issue.
When I get it back together, I'll post a picture of picture of my new scew-on speed
adjustment knob.

oldgoat

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Re: SR-1 governor mystery
« Reply #8 on: October 04, 2019, 02:00:47 PM »
Well I was completely on the wrong track and never would have guessed at what you found. That is a plus you know how exactly how the governor works and I have something to file away in the memory bank .

pinecone9

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How to adjust locating plate on SR-1 with remote start?
« Reply #9 on: October 05, 2019, 08:39:34 AM »
Not your fault, oldgoat.  I should have mentioned that the engine had been smoking and seemed
to have diminished horsepower.   But because those are also symptoms of a bad governor, I
jumped to that conclusion in my first post.  My mistake.

Does anybody happen to know the procedure for calibrating the locating plate adjustment
(which sets the maximum rack movement) on an SR-1 equipped with remote start?  I'd like
to check it before buttoning up the engine.

The procedure in the Lister *Instructions* book only applies to the manual start models.
The Kohler book just reprints the text and diagram from the Lister book.

The locating plate has the same adjustment, but there are no external stops on it and instaed of a
control lever, it has a latching mechanism with a cam that is connected to the fuel solenoid.  It makes
the same start-run-stop movements, but there's no obvious place to put a shim or take a measurement.

My attempts to get a precise measurement of rack movement were not successful. There's no room
to get any kind of measuring device onto the top of the rack inside the housing.   I tried making a special
clamp to mark the position of maximum left travel,  then measuring the distance between the clamp and
the calibration mark with a feeler gauge.  But I can't see the end of the feeler gauge or tell if it is flat. 


There must be some way that they adjusted the locating plate at the factory--it's just not in the books
I have.  The Lister book only covers manual start models, and the The Kohler book reprints the diagram
and procedure from the Lister book (even though many of  these generators were sold with remote start).

I considered drilling a hole in the housing opposite the free end of the rack, then inserting a depth
micrometer.  Afterwards, I could tap it and screwing in a oil-tight plug.  But I'd hate to have any metal
filings drop into the crankcase, and anyway I don't like making field modifications that are irreversible.

BTW, it seems odd that the tolerances on the rack should be so tight: 0.046" - 0.052" with the upper
limit not to be exceeded.   If I want to aim for the upper half of the range, say 0.050", then to be safe
I need to measure with an accuracy of +/- 2 thou.   Obviously, the fuel injector pump that Lister used
was  designed for a bigger engine.   Maybe there wasn't an off-the-shelf one small enough.

oldgoat

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Re: SR-1 governor mystery
« Reply #10 on: October 05, 2019, 10:00:33 AM »
I seem to remember from somewhere the plate was an overload fuel stop and the rack mark was set on the R.H. end of the pump and a 30 thou feeler should fit between it and the stop. But I may be on the wrong track again.

pinecone9

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Re: SR-1 governor mystery
« Reply #11 on: October 07, 2019, 04:51:31 AM »
I took some more measurements of rack motion, but none of them are accurate enough to risk
making an adjustment.    It looks ballpark, and the engine was running OK before the fuel injector
pump clamp bolt worked loose.  So I've decided to leave the locater plate set where it is.  Thanks
anyway oldgoat.

I'm almost glad I took the front cover off--it's a beautiful casting. I wouldn't have noticed otherwise.
I read somewher that in 1938 R. A. Lister built an advanced mechanized foundry at Dursley,
and that the coke-fired furances were replaced by electric furnaces in the 1970s.

Looks like I'm going to need to replace the camshaft oil seal.  There's nothing left of the rubber except
a tiny bit around the front.  Should have been replaced in the rebuild, but obviously it wasn't.   

It's a Gits type.  All I have is a useless Kohler P/N, but a supposedly compatible one is available on-line
and gives the Lister P/N as 201-13190.   Anybody know if this the right number for the SR-1 gear-end
crankshaft oil seal?

Looks like it's necessary to pull the bronze bushing out of the front cover in order to replace the oil seal.
Anybody know if that's correct, and what kind of puller to use?   Do I need a hydraulic press to re-install
the bushing?

I trashed the paper gasket removing the cover--it was stuck to both sides.  I have to get this engine running
before the next big storm, so I had to use Napa gasket-maker.

I was able to guide the speeder screw (with spring hooked) though the hole in the cover using a 4-claw flexible
gripper.  Only took three tries.    Getting the solenoids lifted up a fraction of an inch so the cover could slide
under them was made easier by gentle use of a pry bar.

I have to say that running a screw attached to a spring though a cover is almost as annoying as mounting
control solenoids to one.  Does the word "cover" (as in "remove the...") mean something different in Gloucestershire?  :)

mikenash

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Re: SR-1 governor mystery
« Reply #12 on: October 07, 2019, 07:44:18 AM »
Excuse me if I'm telling you something you already know but the GITS seals are built-up I think?

If you have ID and OD and depth you may simply be able to order it from a bearing/seal manufacturer like SKF

See link?

Perhaps from this you can generate a part number?

Cheers

https://www.gitsmfg.com/shaft-seals/

pinecone9

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My new speed control knob
« Reply #13 on: October 11, 2019, 10:17:36 PM »
In case anyone with an SR wants an easy-to-adjust knob:

10-32 Screw-on knob (with index line added)
10-32 hex flange nut (jams against knob)
10-32 knurled nut (jams against bushing)
#10 synthetic rubber washer (stops oil)
existing Lister brass bushing

All screwed on end of existing Lister speeder machine screw (not slotted on this engine)..

Thanks, Mike.  The oil seal (what's left of it) isn't leaking any oil, so I'm putting that on
the back burner for now.

Current status:  Engine is back together and running.  Front cover seal doesn't leak oil
(three cheers for Napa Permatex Ultra Black!).  However, power still seems low and
exhaust is still smokey even when idling.  I tried removing air filter: no change.  Muffler
and exhaust pipe were recently cleaned.  The engine has run a total of 2000 hours
since the last rebuild.

I'm thinking it might be the timing or a partially plugged injector.   Any easy way to
differentiate between the two?   Or any other ideas?