Timing a 6.2

[Mag]

Anybody know the specs for timing the injection pump on a 6. 2l? My book just says to line up the mark on the pump with the mark on the housing, but I want to know the actual degrees advanced I should be. T. I. A


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2001 3500 4x4 Q. C 6spd H. O, Patriot Blue, 3. 54 L. S. D, U. S Gear exhaust brake, Isspro EGT and boost on A-pillar,EZ
Greig

 

[Power Wagon]

No matter what anyone may tell you from now on, know this. THERE IS NO SPEC!!!!

There, now that that's out of the way, let me explain: GM timed these engines on a dyno, moving the pump to the point where it ran "best". Since mechanical tolerances both inside and outside those engines and fuel pumps are somewhat variable, and, they use a timing chain, not gears, the real timing position will not be fixed. As the timing chain stretches, you need to move the pump ahead to compensate.

Some aftermarket service info does have timing specs, but those are generated by checking a lot of engines and averaging the settings.

Further, unless your pump is fresh and fully updated, it's not really possible to time it accurately. The timing curve is critical to finding the spot of optimum performance, and that pump's timing curve is not very reliable. By the time it has 100K miles, it's performance barely resembles anything on a spec sheet.

As for how to time it: I'd suggest you move the pump to roughly 1/16 to 1/8 advanced (opposite pump rotation... one side of the pump has a rocker lever, the pump internals rotate DOWNWARD on that rocker side - this is true of both ford - international - and gm nat aspirated engines) from the marks lining up. That's where you start. Once you have it there, and have put in a half bottle of stanadyne additive, have the engien warm and a new air filter in it... Take it and wing the snot out of it. Most engines will pour out assorted blue, gray, or black crap out the tailpipe for the first few runs against the governor. It does have a governor, so you really can't overspeed the engine.

ONce you've blown all the soot out of the engine and exhaust, you can then take it out and put it under load, a WOT run up to high speed. If you get a gray or purple haze out the tailpipe as the engine reaches the high end, retard teh timing slightly and try again. The engine should have a pretty solid diesel clatter, but should NOT sound an early PSD. If it is real quiet, advance the timing a bit, and if it's got a harsh rasping rattle when revved or idling, then retard it a bit. If the pump is working right, the injectors clean, and the engine not full of soot, there should be no smoke at all visible no matter how hard you push it. At most, a faint haze. This is not true, if someone has turned the pump up.

Now, after this entirely unscientific means of timing the engine, it usually runs the best it will. We almost never used a timing device to set the 6. 2 engine timing. It was done seat-of-the-pants, and no other setting methodology ever seemed to get as good of results than this.


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ICQ 3807791 Power Wagon
www.my2kcity.com/powerwagon
Mark Koskenmaki, General Diesel Moderator

 

[Boldt's Wagon]

Powerwagon, you said:

"As for how to time it: I'd suggest you move the pump to roughly 1/16 to 1/8 advanced (opposite pump rotation... one side of the pump has a rocker lever, the pump internals rotate DOWNWARD on that rocker side - this is true of both ford - international - and gm nat aspirated engines) from the marks lining up. That's where you start. "

Do you mean 1/16 inch to 1/8 inch between marks? I have a tired 1986 with 150,000 miles 100,000 - 100,000 on a rebuilt pump. The milage used to be 23 mpg now 17 to 18 and I assume a stretched timing chain is the problem.

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'97 SLT 2500, 4x2 LB Club Cab, auto, 230/605 fuel plate and 215 injectors, pillar mount Isspro gauges, BD torque converter, BD valve body, BD Pressureloc, Mag-Hytec transmission pan and differential cover, 3. 54 LSD, white/driftwood, air dam, sliding rear window, towing/camper pkgs, Rhino liner, SS bed caps, stake pocket tie downs, chrome exhaust turn down, SS wheel well trim, Carr steps, Mopar mudflaps, Aerotank under seat toolbox, Cobra 75WXST CB/Firestik, J-MAC louvered aluminum headache rack and tail gate, Mopar flag/tow mirrors, Reese 15k fifth wheel hitch. Mopar Ram hood ornament, Sweet Tooth grill, and white dice. Kennewick, WA.

 

[Mag]

Mark, thanks for the help. This explains why no-one could or would give me any real numbers. Just line up the marks.
I just rebuilt this engine and had the pump and injectors done at a reputable shop a couple hours north of here.
The reason I'm wondering about the timing is the truck is quite hard starting,cold. The glow plugs were replaced and I've got 12 volts supplying them. Also,it smokes like crazy till it warms,up then seems to clearup as it warms. However if I let the truck sit for 10 mins or more it will smoke again even if the wait to start light doesn't come on.
Does this sound like a timing problem or do you have any other ideas for me to try

Greig

 

[Bill Stockard]

Greig,

A common problem with the glow plug IDI engines from GM(5. 7L & 6. 2L) and IH/Navistar(6. 9L & 7. 3L) is that with age, the temeprature sensor starts going bad and they usually short cycle the glowplugs which makes them hard to start when cold. The sensor is in the water jacket part of the intake manifold, screws in about a 3/4" hole, and has about 4 or 5 wires coming out of the plug. It determines the temperature of the coolant and times the glow plugs running time based on the temperature.

These engines run 6 volt plugs on 12 volts so they will heat faster. It the glow plug sensor or the relay sticks it will fry your new glow plugs.

Hard cold starting is usually related to glow plugs or low compression. Since you just overhauled the engine, it must be the glow plug system. These engines are very hard to start if all the plugs don't work or they don't stay on long enough.

Good luck.

Bill

 

[Lil' Dog]

On my buddies trucks we just replaced the 6V glow plugs with 12V plugs on a spring loaded switch. The continuous replacements of relays, temp sensors and controllers was just too much. The 12V plugs had 150,000Km on them and still worked flawlessly and was hard to blow them up no matter how long you have em on for. Makes starting in the cold a very manual manuver, but they always started.

J-eh

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Jason Hoffman
Lil' Mack - 89 D250LE 5 Spd 3. 54 LSD Reg Cab. K&N,"tweaked pump", BD Injectors, Banks Pyro/Boost, 3. 5" Exst tail section straight. E&M Custom seats. Bosch H4, PIAA 80W/80W HdLites. 100W Drv,55W Fogs.
237,500 miles (380,000 Kms) 7850 Hrs. Cummins Power Booster member.
The Original Turbo Diesel

Lil' Mack Pics/March 2001

 

[Doc Tinker]

PW, will doing your recommended adjustments eliminate the soot buildup in the intake?

Doc

 

[Mag]

Well, this morning I took Power Wagon's advice and rotated the pump 1/8" and the smoke is almost completley gone. Truck started better too. If I crank it some more, what will the first sign,I've gone to far,be?
Greig

 

[rickhans]

The 6. 2's in the half ton have an EGR valve (I think that is the correct term - I havenot had one of these engines for several years). The 6. 2 with the EGR I believe is the J engine. The 6. 2 C engine (unless I have the J and C switched) was put in the 1 ton trucks and probably the 3/4 ton. The also had different size valves with different h. p. and torque ratings. On occassion I would get lots of smoke under heavy throttle in my 6. 2 Suburban, and would discover that the hose from the EGR to the air intake had come off or broken. Fix the hose and smoke would go away and I would have more power.

I now have the C engine which has never had this problem because there is no EGR. However, I got reported to the State last year by some citizen doing his good deed because it was supposedly smoking. It was suggested that my engine was probably worn out and needed to be rebuilt or that some other major problem existed. I don't suppose they ever considered that I might be driving a diesel.

However, the next time I have it running (the auto is out again for the 5th or 6th time in 225k miles) I will try adjusting the pump as per above and see if that reduces the smoking. This engine only has about 125k on it and should be good for another 200k miles, which it won't ever see because my Ram gets the miles instead.

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98. 5 24V QC 4x4 SB 3:54 5sp

 

[Lil' Dog]

I don't know if it was on this page or the Weasel page, but with the difference in the two models mentioned someone just puts the intake gaskets from the non EGR system on. This blocks out the EGR and reduces the smoke. The Crankcase vent system also injects some serious oil mist as the engine ages giving even more smoke.

J-eh

 

[Power Wagon]

Originally posted by Boldt's Wagon:
Powerwagon, you said:

"As for how to time it: I'd suggest you move the pump to roughly 1/16 to 1/8 advanced (opposite pump rotation... one side of the pump has a rocker lever, the pump internals rotate DOWNWARD on that rocker side - this is true of both ford - international - and gm nat aspirated engines) from the marks lining up. That's where you start. "

Do you mean 1/16 inch to 1/8 inch between marks? I have a tired 1986 with 150,000 miles 100,000 - 100,000 on a rebuilt pump. The milage used to be 23 mpg now 17 to 18 and I assume a stretched timing chain is the problem.

Yes, move the marks that far...


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ICQ 3807791 Power Wagon
www.my2kcity.com/powerwagon
Mark Koskenmaki, General Diesel Moderator

 

[Power Wagon]

Originally posted by Mag:
Well, this morning I took Power Wagon's advice and rotated the pump 1/8" and the smoke is almost completley gone. Truck started better too. If I crank it some more, what will the first sign,I've gone to far,be?
Greig

It'll get harsh sounding... And, you'll start smoking dark colored. Go ahead and moving timing some more, to see if it helps, but for now, i'd be seriously checking all the glow plugs to see if they all have continuity and also to see if they all come on when you hit the key engine cold.



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ICQ 3807791 Power Wagon
www.my2kcity.com/powerwagon
Mark Koskenmaki, General Diesel Moderator

 

[Power Wagon]

Originally posted by Doc Tinker:
PW, will doing your recommended adjustments eliminate the soot buildup in the intake?

Doc

Teh soot is caused by EGR, as someone said, coming through the big round valve in the in take. If that valve isn't stuck open, you can stop the crud coming in by just unplugging the hose that runs through the air cleaner up to the back of the valve in the intake. Just plug it off. If the valve isn't leaking, the soot will stop. It'll smoke less too.

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ICQ 3807791 Power Wagon
www.my2kcity.com/powerwagon
Mark Koskenmaki, General Diesel Moderator

 

[Power Wagon]

Originally posted by Mag:
Mark, thanks for the help. This explains why no-one could or would give me any real numbers. Just line up the marks.
I just rebuilt this engine and had the pump and injectors done at a reputable shop a couple hours north of here.
The reason I'm wondering about the timing is the truck is quite hard starting,cold. The glow plugs were replaced and I've got 12 volts supplying them. Also,it smokes like crazy till it warms,up then seems to clearup as it warms. However if I let the truck sit for 10 mins or more it will smoke again even if the wait to start light doesn't come on.
Does this sound like a timing problem or do you have any other ideas for me to try

Greig

Almost forgot... There is a cold advance system on your truck... it is supposed to activate the solenoid that bumps teh truck up to fast idle and also one in the top of the pump that advances the timing.

If the thermo switch has failed, it won't bump up to fast idle cold and it won't advance more, both of which will cause blue smoke when cold.

You can check it by turning the key on with the engine cold and testing to see if the solenoid for fast idle is energized, and if the wire connected to the SIDE of the top cover causes a clicking noise inside when it's momentarily connected. You can also test with a light, but that doesn't tell you if the solenoid works as well.