Intro & marble mystery

[scobax]

Hello all, I've been a member for a short while and this is my first post on this forum.

Back in November I bought a nice little '85 1.6NA Golf from a nearby VWDieselParts forum member. Since purchasing the car I have done a full engine rebuild. It's now a good runner and I really love the car. I also have an '81 caddy that I just rebuilt as well as well as a gasser Vanagon syncro Westy. I guess you could say that VW's are in the blood! (Many other diseases live in blood too, for that matter... )

I am encountering the strangest issue and I am hoping that I can enlist the help of the community here to possibly figure this one out. As I said, I fully rebuilt the engine the right way, 12mm block, magnafluxed, cylinder bored, line bored and decked with new .030 over pistons and rings, bearings, ARP studs for the fully rebuilt 12mm mechanical lifter head, new oil pump, timing components, cooling system components, the works. I've got about 700 miles on the Golf at the moment since the build up.

What's happening is that I just can't seem to get rid of the clatter and smoke on the Golf. It's got me worried since I have so much invested in the engine I really don't want to hurt the poor thing right out of the gate.

Before I go any further let me say that I do expect some clatter and smoke under certain conditions like cold starting, but this '85 compared to my identically rebuilt '81 is night and day. The '81 only gives a little clatter during cold starts and doesn't produce much smoke when warmed up. Once warmed up, the clatter in the '81 is non-existent. The '85 clatters throughout the power curve and at idle. I built these two engines at the exact same time over this past winter, and used the exact same components throughout. For all intents and purposes, they should be "identical". The only suspect components between the two are the injectors and injector pumps. Neither injector pump has been rebuilt as far as I know.

On the Golf I have repeatedly set and reset the IP timing using a dial indicator and using the hillbilly method. Still clatters and smokes throughout the adjustment range with a little pronounced marbling towards the advanced side. When it's set right by the gauge method, the IP advance cable does illicit a slight change in run quality and clatter when it's cold.

I have built a very effective and precise injector pop tester, and rebuilt eight different OEM French injectors to specs using Meyle nozzles on 4 and Bosch on 4. All are quite nearly 130 bar each, all within 3 bar of each other. That didn't do it. I have "cracked" the injector lines to try to find the noisy cylinder with no discernible difference across all four. I have stethoscoped the engine while running to try to find the suspect cylinder, but they all seem the same. So I built an injector pump outlet bolt gauge and set the IP pressure to specs. It was a little low. Now it's at 30psi @ 1000 engine rpm warm. No change, clatter and smoke throughout the IP adjustment range. The engine timing is spot on. Triple checked. For what its worth, it fires right up even when it's 25 degrees outside. No blow-by to speak of, and the compression has to be good since it's a brand new build.

At this point, I can only guess that it may be the injection pump itself but I'm not sure how one makes that determination. I guess I can pull the pump off of the Caddy and run it on the Golf, but there has to be a more scientific method...right?

I don't know how to determine the pump family, or exactly what "yellow dot" pump might be. Any guidance on this would be very much appreciated.

I do have a spare pump off of a Quantum TD. If push comes to shove, is there any way that I could use this pump for a while as a patch while I rebuild the one that came on the car? It has a different "top" on it, but that looks to be something that I might be able to swap out with the NA pump. Not really sure. the Bentley isn't much help at all.

Well, thats it. Any suggestions would be most graciously appreciated. this one has me stumped.

Thanks!

Scott

[coke]

A pump off a 1.5L can be yellow dot or non yellow dot, but either way I believe they both had a steeper advance curve. Look at the part number on the pump. If it ends in 107 A, its likely a 1.5 pump.

Sounds to me like the pump though. Did you check your valve adjustments? You indicated its mechanical versus hydraulic. All the valves within spec?

[scobax]

Coke,

Thanks for the quick reply. I'll check that pump number in the daylight hours. As for the valves, ya know, I trusted my machinist on this one since he rebuilt and assembled the head. They set the clearances. I never checked it afterwards. It's got new valves guides and lifters with a polished cam. The head was machined and pressure tested prior to build. They are a reputable local shop that is rather familiar with the 1.6 diesels but crazy things can happen.

I guess I'll check my clearances tomorrow, too.

Thanks for the insights, I'll report back after I check these things.

[coke]

How did it run prior to the rebuild? I just said valves because you had mentioned it had head work done to it.

[scobax]

well... to make a very long story short, the night that I bought it I drove it a total of eight miles before it overheated and died a horrible death. The temp gauge and low coolant light weren't working at that particular moment unbeknownst to me so I had no warning that the lower radiator hose had blown off until it quit running. After that, the head was warped like a pretzel and the block was cracked. I scrapped the whole mess and started with a "new " block and head. From that eight mile ride, I can't really say how it was acting since it was new to me and it was night and it was raining, well, you get the picture. A series of unfortunate events.

I ended up leaving it with the original owner who very graciously refunded my money but I couldn't resist, I went back the next week and picked it up with a trailer!

[Dakotakid]

Who was responsible for the measurement of the piston protrusion and selection of head gaskets prior to fitment of the head?

[the man 53]

^ and also...

A new properly built engine will be "tighter" than one that has several hundred thousand miles on it. When your engine gets over 6,000 maybe a little more miles, it will "loosen" up a bit. At least mine did. It was very noticable for me. Going down hills the car would coast in gear well, before it would almost come to a stop when trying to coast down hill. It was still loud and clacky, but it changed the pitch of the sound and seemed to quiet down some. Mine always did have a little smoke especially at start up, but if you want to eliminate that completely buy and 8v gasser.

[scobax]

Who was responsible for the measurement of the piston protrusion and selection of head gaskets prior to fitment of the head?

Good point.

I measured the protrusion multiple times across all cylinders. The '85 in question took a two notch, and for what its worth the '81 Caddy took a 1 notch. That's the thing, I've got these two engines side by side both rebuilt at precisely the same time and the same way yet one's noisy and smokey, one is not. Obviously, there are small differences like head gasket thickness and valve clearances etc., but ultimately regardless of the variances in clearances, the idea is to end up with essentially the same thing.

Mine always did have a little smoke especially at start up, but if you want to eliminate that completely buy and 8v gasser.

An 8v gasser ?! Oh, that hurts. The smoke that I'm talking about is not only at start, it's through the temp and rev range. It's excessive. Black and whiteish combination depending on load. Mileage seems a little low as well that's why I'm focusing on the injection.

To be clear, I did achieve a fairly quiet idle at one point right after I rebuilt the second set of injectors, but it was still pretty marbley (is that a word?) at mid and high RPM's so I adjusted it out with the IP timing to have a less sharp clatter while making power rather than at idle where the stresses are less. This proved to me that there is a possibility of achieving a state of marble-free running with this engine and it probably isn't some other type of mechanical error, the trick here is to expand on it so that it is more of the normal state rather than an isolated condition.

The real unknown is this injection pump. It's the only component that has not been rebuilt. I just don't know how to tell if it a "good" one aside from checking the internal pressure, making sure that the advance has some effect and looking for external leaks. How does one test an injection pump for output pressure?

That '81 Caddy is the benchmark. It's strong, efficient, smokeless and marble free throughout the rev band.

Keep 'em comin'!

[82vdub]

Black smoke represents too much fuel, and blue/white smoke represents poor combustion.

I'd check compression ratio on the engine that's giving issues. See if the rings seated properly or if you're suffering with low compression.

Have you rotated the engine with a wrench on the crank just to make sure that you don't have a hard piston to head/valve "kiss" situation going on?

Also, since you have two identical engines that both run, swapping the IP's will tell if the problem stays with the engine or the IP.

[TylerDurden]

Ja, I wouldn't call swapping the pump unscientific... I'd call it a PITA. But it seems the best/fastest/cheapest way to isolate the issue to the pump (or not), IMO.

[Dakotakid]

I totally rebuild 3 engines two years ago. Two hydros and one mechanical.
They all run different and I set them up to run very well when warmed up.

Have you turned the load screw on the pump back?
Yes, these pumps run different with age due to wear characteristics.

[scobax]

Update:

What an afternoon! First off, I double checked all of the valve clearances, all within specs. Next, I warmed it up and did a compression test. 480-485 across the board. then I checked the IP timing, .97mm. Right on the money. So then, I backed out the load screw a bit, big differences in smoke (and power), but not necessarily marbles. So then, I just bit the bullet and swapped out the IP with the one on the Caddy. Bingo. Night and day. Good power, less smoke and way fewer marbles on that plate. I'm still not entirely sure why this is so, but I will read up some on the inner workings of the IP to get a better grip on it.

Thanks to all who passed on advice and suggestions, it really helps to have a few more minds working on these types of things.

[coke]

Best bet is to get a different pump. In my experience, opening them up is opening a can of worms. Some people have had excellent luck with it, others not so much. There are just so many parts in there and problems aren't always apparent to the naked eye.

[Fatmobile]

Would be nice to know what makes this pump run bad, maybe find a fix.

[the man 53]

I would have loved to hear and see a video of it running. If it was a pump issue then swapping it would have taken it all away. Injectors and valves could be a cause. I didn't catch if you had the head done on one or both of these or what the valves had done to them.