Two cold start oddities..

[wolf_walker]

Two things. 86 ME code NA 1.6 with a 107A pump in 81 caddy.

It fires up beautifully, one glow cycle(new plugs) runs smooth
and idles fine with no smoke(new injectors).
Battery is a 750cca Interstate that shows no sign of a problem
and isn't very old. Alternator is charging in spec checked with meter.
After starting, when I blip the throttle to excite the alt, it puts a
HECK of a load on the motor. Idle drops way down, not near stalling, but it's a heck of a drop, and this is a 107A A1 pump so no idle RPM advance with the cold start handle(which I don't need to use, not much diff, but it does work). Larger battery? I think this is the size I always used to run.
I know this isn't unusual behavior since it just ran the glow plugs and then started the thing and it's chilly out, but it seems a bit extreme, this drag.
I'm reminded again I always wanted to fit a more modern alternator to one of these things.

2nd thing, is it's marbely as all hell when cold. Not at idle, but any rpm much over, like driving down the street the block or two to the main road, it sounds down right nasty. Again I know this isn't unusual, but it's a bit extreme. I've been retarding the pump timing a bit at a time and having gone from 1mm to .93 so far I can't tell a lot of difference, and don't really want to loose my advance/power/mpg. No noise when warm, or after a few minutes of running even. It's just brutally clattery cold.
I suspect I could retard it and hush it up, but I don't wanna if I don't have to. It also don't feel like it has excessive dynamic advance when it's warm, but I don't have a way to check it really. This pump is old, but seems to work alright otherwise. I have another I re-sealed and has been test run a little I might swap on and see.

Thoughts?

[Fatmobile]

So you know a 107A is a 1.5 pump?
Have you tried pulling the cold start?
What gave you the idea a 107A doesn't have timing advance when the cold start handle is pulled?

One thing I have noticed when timing the 107A pump is the dial gauge only jumps .005" when the lever is pulled. I don't think that's just the yellow-dot pumps.
The 107AG and other 1.6 pumps jump .010".

[wolf_walker]

It might be a 107AG, been reading Hagars book-length thread for awhile, 107A on the brain. Both the pumps are originals to 1.6L's though.
Sorry, tired.

At any rate the cold start does "work" I don't remember what the movement was but I checked it last time I had the gauge in the back of the pump and it did move. For operational use it works, I can hear a change, but not a lot. It feels what I consider normal, pulling on it, both with the handle and just the lever.

My "other" 1.6 in the rabbit, original mech head motor that I have done nothing save re-seal the pump, acts like normal, runs like crap unless the cold start handle is pulled. I think I static timed it at .90 or so. It's injectors are filthy, so is the rest of it. Later project. The pickup motor runs better, as it should, there is something different with it though.

[82vdub]

My 82 has more marbles when its cold out and the engine is cold. Doesn't sound as loud as you describe yours, but still louder than when the engine is warm. For your situation, it could be the timing, or a bad injector (or more than one).

For the engine RPM issue, mine does this as well, but the RPM drop doesn't sound as significant as you describe yours. However, in the cold weather (like we're having now), it's really a different RPM. I've just never paid any attention to it, as long as everything's charging as it should etc. I know thick oil in a cold engine really effects the RPM of the engine when it's cold. A combination of just started engine, thick cold oil and the alternator trying to recharge the battery could likely result in a much slower engine RPM. Keep in mind that it may only take an RPM drop of something like 50RPM to really make the engine shake more, giving the impression that it's really bogged down. These engines are definately rattle-boxes.

[Quantum-man]

So you know a 107A is a 1.5 pump?
Have you tried pulling the cold start?
What gave you the idea a 107A doesn't have timing advance when the cold start handle is pulled?

One thing I have noticed when timing the 107A pump is the dial gauge only jumps .005" when the lever is pulled. I don't think that's just the yellow-dot pumps.
The 107AG and other 1.6 pumps jump .010".

Interestingly around the basic timing region of around 1mm, for the 'normal' 1.6 pumps, each flywheel tooth's worth of rotation, [2.73 degrees of crank] equates to between 5 and 6 thou thrust.
Thus, basic pump advances close to 5 degrees with cold start lever. But does that mean that the yellow dot only advances half that?
I see original spec timing was only 0.83mm. Bosch injectors set between 120 and 130 bar, .
Funny how Bosch kept advancing the pump's timing setting over the years, confirming that they were still experimenting...

[tawney]

Regarding the excessive marble noise when cold, one interesting thing to try would be to put a pressure gauge on the pump to see what the internal pump pressure is when cold compared to when warm. The viscosity of the fuel would be greater when cold which could result in higher internal pressure, maybe enough to get too much timing advance even at low rpms. Are you adding anything to the diesel fuel?

Another issue that came up recently in a post by Fatmobile, is the possibilty that a vacuum on the fuel-supply side of the pump could increase the amount of advance since there's a passage from the front side of the cold start advance to the IN side of the vane pump. A vacuum gauge on the fuel line to the pump would help to diagnose this possibility; as far as I know, no one has measured the effect of fuel vacuum on timing.

[wolf_walker]

That's an interesting thought on the restriction in fuel flow. I had been asking myself if there was any way for the timing to be advanced when cold other than fuel viscosity as well. Additive wise running ashless tcw3 2cycle oil for lubricity, and I think a bottle of redline DFC.

It is a 107AG pump, just for the record.

I'm leaning toward putting the other pump on here this weekend.
This one has been sitting for about three years wrapped up in the garage,
I'm amazed it works. But it does, bless it. Runs good near as I can tell
when warm too, smooth to redline, nothing funny at all. No marbles, at all.
Also toyed with the idea of timing it by ear, but I suspect it'll take a lot more timing warm than it will cold. I haven't physically checked the injectors myself but they are new Bosch(new reman and two NEW new) and I don't hear unhappy injector sounds warm or cold. It it isn't clattering cold at idle, just above it. Quite strange.

So, pump swap and compare? I have to do a head gasket sometime soon, leaking oil at front as usual, no other symptoms. Should swap the pump before that I guess.

[tawney]

I wouldn't swap the pump; too much work for an uncertain result. Actually I would probably just ignore this too-much-marble-sound, but if you're determined to find out where the marbles are coming from, here are a couple ideas. First, I would just retard the timing a little. Next, if you've got two pumps maybe you have two IN bolts? Put one on the OUT bolt location when it's cold and start it; see if that changes the marble sound; it will prevent any internal pump pressure, thus no timing advance. It will run fine like that at low to mid rpms; I checked it on my Caddy. If that quiets the low rpm marbles, then I would suspect that your fuel additives are increasing the cold viscosity too much. With no restriction on the outflow of fuel from the pump, though, it will move a higher volume of fuel, so you can expect to create a vacuum on the supply side. To check the remote possibility that vacuum on the supply side of the pump is increasing the advance, you could pull fuel out of a separate container through a small in-line filter.

After that, just live with it; it's a diesel.

[tylernt]

Your '86 is a Mk2 which means it has a glow plug "afterglow" system to help the engine warm up faster (and to reduce emissions). When you blip the throttle to excite the alternator, the glow plugs immediately put a 50A load on it as they continue to glow for the next few minutes.

Bigger alternator won't help, 50A is 50A pulling on your alternator belt.

[wolf_walker]

Your '86 is a Mk2 which means it has a glow plug "afterglow" system to help the engine warm up faster (and to reduce emissions). When you blip the throttle to excite the alternator, the glow plugs immediately put a 50A load on it as they continue to glow for the next few minutes.

Bigger alternator won't help, 50A is 50A pulling on your alternator belt.

A2 motor, is in an 81 pickup, I guess the relay could have been swapped at some point, don't remember. Lot of miles and years on this thing. It's a thought though.

[wolf_walker]

I wouldn't swap the pump; too much work for an uncertain result. Actually I would probably just ignore this too-much-marble-sound, but if you're determined to find out where the marbles are coming from, here are a couple ideas. First, I would just retard the timing a little. Next, if you've got two pumps maybe you have two IN bolts? Put one on the OUT bolt location when it's cold and start it; see if that changes the marble sound; it will prevent any internal pump pressure, thus no timing advance. It will run fine like that at low to mid rpms; I checked it on my Caddy. If that quiets the low rpm marbles, then I would suspect that your fuel additives are increasing the cold viscosity too much. With no restriction on the outflow of fuel from the pump, though, it will move a higher volume of fuel, so you can expect to create a vacuum on the supply side. To check the remote possibility that vacuum on the supply side of the pump is increasing the advance, you could pull fuel out of a separate container through a small in-line filter.

After that, just live with it; it's a diesel.

I can live with it, just sounds rough on the poor thing.
Good idea, the out bolt swap. This weekend I'll try it.
Part of my wanting to run the other pump is to put a few miles on it
and see if it's happy. I put new seals in it after I bought it and it was
leaking form the input shaft quite a lot. It's on the rabbit and dry and run(and likes the cold start handle pulled out to be smooth on cold start, unlike mine that don't seem to care either way), but it'll be awhile before the rabbit is driveable other than around the yard.
It bares mentioning that this thing sat with a half tank of fuel in it for three or four years till these last few weeks. I drained the tank and what came out was a little thick but still ran out just fine, ditto what was in the old fuel filter(twice changed now), I was lucky there. It's possible the pickup is semi-clogged I guess. It does seem to run well when warm.
This is verging on a dumb question but can I just T in a vacuum gauge on the inlet side and see if there is over much suction to check that? Seems like I'd have a loss of power at interstate speeds/high rpm and throttle if it was restricted though, haven't noticed any. Curious.

[Fatmobile]

Yes, you can just "T" a vacuum line into the fuel line.

[wolf_walker]

Yes, you can just "T" a vacuum line into the fuel line.

Excellent, I'll check that and play with the timing this weekend.
Thank you for the suggestions everyone, I'll report back after some fiddling
around.

[wolf_walker]

As a small update, and all I'll have time for between the cold and time contraints, I retarded the pump timing maybe a MM using a reference mark on the pump and bracket. It did start a little rougher cold and smoothed out with the cold start handle pulled, which I consider closer to normal. It still had a hell of a lot of marble/clatter till warmed up, though I swear if you grit your teeth and let the rpm's climb a little it get's better. Till you shift.
And it's a bit weaker, getting to 65 in 5th on a hill is a no-go now. It was touchy before but hey, it's a NA 1.6D. I'll put a dial gauge on it and see where I actually adjusted it to later. Some very careful listening before retarding the pump did let me hear some slight marbles at hot idle and at light throttle in 2nd or 3rd, but very slight.

I wonder if this isn't a matter of low internal pressure/dynamic advance. If I set static timing to where it has a reasonable amount of noise cold, it'll then be a dog till I find a way to cobble a gauge together.

I've never really had this issue before, how bad IS the noise for the motor? It sounds like hell frankly when cold trying to drive it, we all know they take forever to warm up with no load on them, I turn the lights on but it only helps some. Will it actually hurt anything? It can't be kind to the rob bearings or pistons.

[tawney]

Regarding the noise, if retarding the timing has made no difference, I would start to wonder about other possibilities; there's no chance that you've got valve/piston contact?

As I understand it, there's no unusual noise at idle, at high rpm, and when warmed up ; it's only a problem just above idle when cold? What's the history of the pump? The timing device piston is held in its rest position by a spring; the other end of the spring rests against the cover that you can see on the front of the pump, (opposite side of the pump from the cold-start lever cover.) Between the spring and the cover is a washer, and there's another washer on the other end of the spring where it makes contact with the timing piston.

So, in the realm of wild guesses: If those washers have been left out, or if the spring has been shortened, or something similar, it might be that the spring tension is insufficient and allows too much advance at low pressures. Decreased spring tension wouldn't necessarily affect timing at idle, and if the old vane pump isn't quite producing higher pressures as designed, it wouldn't result in too much advance at higher rpms. Pulling the front cover, the washers, and the spring is something that can be done without removing the pump. You could even compare to your other pump.