'86 6.2l Suburban revival advice

[dsparg]

I recently purchased a 1986 6.2l GMC Suburban. The truck has been garaged and unused for over 2.5yrs. I am in need of advice on the steps I need to take to safely get the engine started again. Any and all help is greatly appreciated.

[Robyn]

Welcome to TDP :D:D

Change the oil, filter
Fresh fuel filter, air filter and such and you should be good to go.

Unless there is reason to believe there is contamination I would charge the batteries and have a go at a start up.

Warm it up then do the service work.
Check coolant and be sure its clean, green and in good shape.

Do the fuel filter and such last unless it is balky on the startup.

Once warmed up and with strong batteries the fuel filter change and bleeding will be a snap.

Any other issues, just ask :)

Folks here are always willing to help

Robyn

[DmaxMaverick]

2 1/2 years is a significant time, so I'll add:

Check all the belts, hoses (including heater hoses), or any other rubber under the hood. Any dry-cracked rubber should be replaced before trying a start. They will fail in very short order.

Check the power steering and tranny fluid condition and level. A dry/contaminated pump will self destruct.

While checking/replacing the air filter, be sure to check the entire intake tract. Critters really like to set up house and home there, and not always where you can readily see it. You can start/run the engine with the intake plumbing (pipes from the grill to the air cleaner) removed from the air cleaner hat. Clean these parts very well before using. If the air cleaner element appears damaged/compromised in any way, inspect the intake manifold VERY well.

Check the glow plug system. Pull, clean, test each one. Or, just replace them, if they are original 9G's. Use 11G, 60G or Quick Heat plugs. The 9G's, if they haven't failed, will much quicker after a long period of non-use (corrosion). And, when 9G plugs fail, there's a fair chance they will swell and become stuck in the head, or break off into the cylinder (not a good thing).

Squirt some WD40 into each GP hole while they are out, and rotate the engine by hand. This will smooth up the cylinder walls and knock off any surface rust that's developed. Better to do this slow, than fast, like when starting or running. Keep in mind, any oil is fuel in a Diesel. I suggest after the hand turning to use the starter to turn it over several times to blow out the cylinders.

Before you try to start, remove the FSS wire (pink wire at the IP) and loosen the fuel fitting at the pump. Crank the starter until you get a good stream of fuel at the fitting. A good idea to do this while the GP's are removed.

Always keep the batteries at full charge. The engine may not start easily or right away, and poor batteries will burn up the starter (and not start the engine).

Once everything is clean and flowing/turning well, give it a go. You may wish to loosen some injector lines at the injectors to help bleed air from the injector lines. It may start right off, but if it doesn't, loosen the lines until you get the line nuts wet with fuel.

Much of this may seem like overkill and tedious, but it will serve you well years later.

[dsparg]

Thanks for the great advice, ladies and gentlemen. I'll post the results of my efforts when I can. This will be a slow process as it is an evening project for now, but I hope to have her up and running soon. You're help will certainly speed up that process. Once she's running we'll be discussing how to increase power & torque. :D

[dsparg]

Well, I got her running. Now I'm working on getting her dependable. I'm having a couple of problems that I'd like your thoughts on.

1) The engine cranks and cranks and cranks before it starts. You can tell the cylinder(s) are trying to fire, but it takes a good 45 seconds of cranking before she fires up. I'm changing the glow plugs tonight. Found 2 bad, so they all get replaced. Could that be the problem?

2) After the engine is warm, if I return to the suburban to start it again it will not start. In this scenario you can tell none of the cylinders are firing and I believe it is because the glowplug system is not engaging. When the engine is warm, when I turn the key "on" the glow plug light does not come on. Bad glow plug controller???

I still need to replace the fuel filter. Any helpful advice on completing this task?

Thanks for all your help.
Dan

[dsparg]

Forgot to ask this. I read another post somewhere that there is a way to operate the glow plugs manually and not worry about the controller. Any insight on this idea? Bad idea, good idea? Let me know what you think about that.

[DmaxMaverick]

Definitely change the fuel filter, and be sure you are feeding it clean fuel.

Glow plugs can and do cause labored starts. The lack of a glow plug light indicates a no-glow. The light comes on any time the plugs are powered. You should also be seeing white smoke from the tail pipe during these long cranking episodes. No smoke could indicate no fuel. Verify the lift pump is pumping fuel (and not air, like from a leak).

Manual glow control is not something new, or uncommon. Very easy to do (and cheap) on an 86. If you replace the plugs with AC60G's, you'll likely have to modify the glow cycle, in any case. They take about twice as long to heat up, compared to the originals. Try a search of the forums for manual glow. If you don't find what you need, let us know. If nothing else, replace the glow controller. They aren't expensive for the 86, and are fully self contained (not multiple parts, like pre-85).

Also note, you won't get too many 45 second cranking episodes before you fry the starter. You should do no more than about 20-30 seconds, with 2 minutes between attempts.

[dsparg]

I resolved the cranking issue with the starter. Discovered that the brushes were loose and bad on the starter. A $40 repair. The starting RPM's are much better now so she starts much more reliably now. From time to time when the engine is warm I still have to get under the hood and "jumper" the glow plugs to heat the cylinders. Doesn't make sense to me that a hot engine won't start unless the cylinders are preheated. I'm considering replacing the glowplug controller, but then start thinking manual glow control. I think I'll do more research to compare the cost of both options. Any opinions offered would be appreciated.

One other problem I had when I bought the suburban was that the headlights wouldn't work at all. All the marker lights would come on no problem. Brake lights and turn signals worked fine, just no headlights. I tracked the problem down to the high/low beam selector switch. I currently have a jumper in place just to have headlights, but I'm ready to install a new switch. The mounting bolts are on the top of the column. Any tips on getting to them without taking the entire dash apart? By the way, I didn't discover the location of the high/low beam selector switch until after I had the steering wheel and locking plate completly apart. Ha!

Thanks again for all your input here.

[DieselCrawler]

but I'm ready to install a new switch. The mounting bolts are on the top of the column. Any tips on getting to them without taking the entire dash apart? .

It's been a few years, but if I recall, I was able to get to the switch with the column in place, using a 1/4" drive ratchet and socket, and my little hands. That may be the key, my hands are little... and contorting my self in such a way as needed to get up in there, laying on my back on the floor boards, head wedged between the brake pedal and something else hard and painful...

Loseing up the column might be worth it, there's not that much keeping it in...

Good luck...

[dsparg]

Thanks for all the help so far. Now I have an electrical question.

The headlights flash on and off randomly when the high beams are on. When I turn them on everything is fine, but after 90 - 120sec from when the highs are first turned on they start to flash. The running lights do not flash with them, only the headlights flash and only when on high beam. Once I switch back to low beams everything is fine.

Something in the circuit is heating up because after they start flashing on and off, if I switch to lows and then back to highs the time it takes for them to start flashing again is affected by how long I have them on lows. I just can't figure out the cause. The headlight switch has been replaced and the high beam switch has been replaced. This problem existed with the old switches. The diagram I have doesn't show anything else in the circuit. All four lights have been replaced too, by the way.

Any ideas?? Thanks in advance.

[NH2112]

I'm considering replacing the glowplug controller, but then start thinking manual glow control. I think I'll do more research to compare the cost of both options. Any opinions offered would be appreciated.


Well, for the manual setup you're looking at maybe $50 total for one of these

http://www.napaonline.com/NOLPPSE/%28S%282yem4u55c5cetq55dh0bjmzm%29%29/Detail.aspx?R=ECHST84_0215714960

one of these

http://www.napaonline.com/NOLPPSE/%28S%28sfocfga2fwtd31yndnox0cfc%29%29/Detail.aspx?R=ECHSTB6301_0215715093

And maybe 6-8 feet of wire & some heat shrink terminals.

[Robyn]

The headlight circuit could have a circuit breaker installed instead of a fuse.

The breaker could be failing.

Check the fuse panels for the headlamp fuse/breaker and see whats there.

A poor connection of the fuse if used can cause this too.

The connection being poor causes heat to build and then the connection breaks and as it cools it reconnects ?????


Just some thoughts


Missy