New member 6.2 Questions

[fire846.2L]

hello to all, new member here. I have did some searching on some issues I am having and still not sure on the total issue so ordered the manual and became a member here.

Ok, I just bought a 84 Suburban 6.2L 3/4ton 4x4 showing 07,xxx and was told it was 107K but now thinking maybe more 207 or 307.

Ok, it was running on cooking oil for one thing from the mechanic that owned it before the owner I bought it from who had it for 5months then sold it to me. At this time he ran diesel as well (too cold for the oil tank in the back).
It really seems that the less I push the pedal the quicker to pick up speed it is. It feels like it is surging at times and will not go over 60 on a flat road.
No major smoke, was told tranny was rebuilt, and have not yet removed all the cooking oil setup and tank as I was only gonna run diesel.
I have cleaner in the tank right now from the diesel shop that they recommend to help clean out the cooking oil. I tried to cross a road and it took off then fell on its face untill a few seconds and then slowly picked up speed. I did crack the drain on the fuel filter (firewall mounted) and let clean diesel run out. Then had an issue getting it to start then finally it primed and fired.

2nd problem is once i get over 10mph it makes a noise that sounds like the noise of you putting the car in park before it is in park (clicking noise) and it also just started to clunk right before I stop, and sometimes once I take off. I did notice if i put it in 4 hi that it dont make these noises so was figuring it was something in the T-case.

Is there a few good cheap quick maintenance things I should do other than oil and radiator fluid?

Thanks for any help, like I said its my first diesel and really would like to keep it diesel.


Chad - Middle TN

[Robyn]

Hello and welcome to TDP

First off replace the fuel filter/filters and give that a whirl. A dirty (plugged filter) will cause just what you report.

Now to save yourself a load of grief, do the changeout this way.

Warm the engine so it will spin easily and start easy too.

Shut it off and then crack the filter air bleed on top to relieve any pressure.

Drain the filter and remove.

Replace the filter with a new one .

Unplug the large red wire from the injection pump.
This will allow you to crank the engine without it starting. Crank the engine with the IP unhooked and the filter air bleed open until clean air free fuel comes out.

Once you have clean fuel coming out the bleeder, close the bleed screw.

Niow hook the Red wire on the IP back up and start the rig as usual.

This will likely get you up and flying again.

With that cleaner in the system you may have to change the filter a couple times.

As far as the Noisde issue goes there are many things that can make noise.

Get it running good and then we will beat on the noise issue


Missy

[fire846.2L]

Wow, quick reply.
Yes, I have ordered 3 fuel filters as I figured I would run through some.
I also planned to remove the front drive shaft and if noise went away then that would help me eliminate it.
I did order new u-joints and new shocks. It has new exhuast and was told the tranny was rebuilt recently.
As soon as it warms up a little bit more I want to change the rad hoses and flush the system out with some water.

BTW- where is the IP located? (want to be sure).
Is replacing the injectors a simple thing most people do on their own?
Once I get all the oil out of the fuel system I was thinking about swapping them out as they were $40 each and since my mileage is close to the time they go out.

Chad

[fire846.2L]

Well, ran the cleaner thru most of the tank (at 1/4 now) and swapped the fuel filter. Wow, what a difference! This truck runs awesome!
The noise in the trans is something to due with the t-case.
When it makes the noise I can slow down to about 10mph and put the K20 in 4 wheel high and then take it right back to 2 wheel high and the noise is gone. Parked it while I went into auto zone and when I took off down the road the noise was back so popped it back in 4 high and 2 secs put it back in 2 high and no more noise all the way home.
Wonder if the linkage could be off when the tranny was rebuilt.

Man, im getting excited!!!! She does run good! No to do the mods to get a bit more power so I dont have to go to a turbo.
Chad

[fire846.2L]

anyone have any ideas on this t-case / trans issue?
My transmission has been rebuilt so wonder if there is something loose.
Not an automatic trans person at all.

Just really strange how the t-case some how gets a little off and by me putting it into 4hi and then back to 2hi takes care of it as long as I say in drive and dont move the gears at all.

[Robyn]

Sadly without actually hearing this noise, it is tough to come to any meaningful conclusions.


84 Burb 2500 will have a TH400 tranny. Not too much in these that can make much in the way of clicking noises.

My best suggestion would be to get it safely up off the ground so you can run the thing and then listen up close and see where the noise is coming from.

Be careful and use any and all safety precautions when getting up close and personal with moving shafts and such.

Having it on a hoist would be great, if not jacks stands will work.

Keep us posted


Missy

[NH2112]

One thing I've seen with this era of trucks is the wrong fluid in the transfer case. Make sure it has ATF in it, and that the level is correct. I sold a spare NP208 to a guy who bought a truck with gear oil in the transfer case. His original complaint was that the transfer case wouldn't stay in 4WD, he drained the fluid and that's when he found the gear oil. Putting ATF in didn't help matters very much and soon it wouldn't even go into gear. When he took it apart he found the shift forks nearly completely worn away. I don't know what kinds of noises his was making, if any, but I could imagine being partly in gear could make a sound like the park pawl trying to catch a moving gear.

[crashz]

The shift forks in my '83 (NP208) wore out completely and allowed the case to jump gears. It worked fine up until it left me stranded one day. Maybe there is enough play in the case that its almost engaging 4wd or low range? I kind of doubt it though.

The transmission replacement may have something to do with it. My guess is that the linkages to the t-case may be out of adjustment, loose or worn. The threaded adjustments are tough to work free if rusted up, so the tranny shop may have left it alone. Even a rotted transmission mount could be causing a linkage problem.