Purchased my 1st 6.5 - Some questions!

[ryan.g]

Hello everyone,

This is my first post here. Tonight I just brought home my first 1993 6.5TD GMC Sierra C/K 3500. It has the 5 speed transmission. Anyways, I had a few questions about the truck as it is not perfect and could use a little care.

1) The truck has sloppy steering. From my searching, some people say a steering stabilizer and some say the steering box. Any input as to what the most common cause of play in the steering on these trucks is?

2) The truck seems like the alternator is backfeeding causing the batteries to drain if the truck sits for a while. When started, the voltage reads just over 9 volts and fluctuates when the glow plug light flashes on and off. It will read around 12 when driving down the road.

3) Where is the best place to purchase body parts such as door panels? I know of LMC but is there anything better?

4) Is there anything I need to know about this truck? I don't know much about it. I'm not wanting to try and get more power out of it, just drive it.

Sorry this is my first post and thanks for any and all of the help I can get!

Ryan G.

 

[3500GMC]

Welcome to TTS Ryan.

Sloppy steering is a combination of parts with some 'play'. Ball joints, idler arm, pitman arm, tierods and steering box. If you are mechanical, this is very fixable for a modest cash outlay....Have a helper rock the steering wheel L+R while you are under there looking at stuff.. Drop the front skid plate beforehand. Try and isolate the biggest 'offender' and go after that first.

The tach runs off the ALT, does the tach register RPM? Maybe there's some wiring issues.

Door panels (interior) can be had from the boneyard.. Don't forget Tahoe/Blazer and Suburban fronts have the same usable door panels.. Usually they are in much better shape than in a pickup truck.

Your truck will be a good one, once you get things whipped into shape. The 93 model year pickups are the last year for the Stanadyne DB2 (mechanical injection pump)...

Do you know any history about your truck?

 

[tanman_2006]

93's are very reliable and see very easy on the fuel esspecially with a 5 speed.

Mine took a new idler arm and pitman arm to fix BAD steering problems. I threw in tie rods just for good measure.

The biggest concern with a mechanically injected (93 DB2 pump) is making sure it has a good fuel supply from the lift pump, it makes a HUGE difference when working. Also the glow plug system needs to be working good.

Make sure your radiator is clean inside, outside, and in between.

As for your Alt charging problem that might be normal. The early 90's trucks had problems with low charge readings, check with a volt meter at the batteries and see what the alt is charging them to before getting to carried away.

 

[WarWagon]

2) The truck seems like the alternator is backfeeding causing the batteries to drain if the truck sits for a while. When started, the voltage reads just over 9 volts and fluctuates when the glow plug light flashes on and off. It will read around 12 when driving down the road.

Check grounds, battery cable condition for internal corrosion, add a ground strap from the frame and body to engine. Cut out the main battery feed (positive) and replace it with a fusible link and wire. This is the wire going from the passenger battery and attempting to short out on the battery tray, then going between the exhaust manifold and engine by the starter, with the insulation burned off no doubt, to the main junction under the plastic cover on the pass side firewall. Replace the alternator as required with a CS-144 and modified brackets paying attention to the special diesel pulley size. A larger wire on the alternator also helps. Check fuses by removing and cleaning them as this can cause low voltage as well. use a volt meter to verify accuracy of the dash gauge and troubleshoot connections from there...

Glov box light, dome light, aftermarket stereo's... Disconnect one battery and load test both. Charge them 1 hour and let sit overnight to see if you have a bad battery - replace in pairs.

4) Is there anything I need to know about this truck? I don't know much about it. I'm not wanting to try and get more power out of it, just drive it.

How many miles on it and how many on the 100K life injectors? How old is the fan clutch? Covered in it's own blood? Look at cooling system upgrades and cleaning behind the oil coolers.

Ryan G.

Welcome! See above.

 

[Burning oil]

If you want more MPGs cut the muffler off or better yet a new 4" exhaust. Also a air intake. On my old 93 it was worth 2 MPG. That will pay for itself quick.

 

[tanman_2006]

In the quest for economy you normally stumble upon more power.

 

[ryan.g]

Thanks for all of the replies! I love the truck! However, upon replacing the alternator, I caught the smell of diesel fuel. I looked and sure enough, the cavity under the fuel filter was full of fuel. I removed the fuel filter housing, gave it a good cleaning and replaced fuel filter. Got everything put back together and on the truck. Now, I have a fuel leak like no other but it does NOT seem to be coming from the filter housing as the cavity below is dry. It almost seems like the fuel line may be cut or something between the firewall and the motor somewhere. The fuel is spilling all over the back of the motor and right around the front of the transmission.

Aside from that, I was told also that you can test draw on your battery by simply disconnecting the - lead and hooking the clamp to the cable while touching the terminal. If it lights, you have draw which will cause the batteries to die over time. I tested mine, no light. I also replaced the alternator. Will see how it starts in the morning.

Thanks everyone for the warm welcome and all of the help so far!

 

[3500GMC]

View of what your engine looks like intake manifold and tstat xover OFF.

Also there are 2 rubber lines tucked (buried) in the rear (firewall) that is fuel feed (3/8) and return (5/16)

 

[ryan.g]

Thanks alot for that picture. I am loosing alot of fuel somewhere. I will check it out when I get home today!

 

[ryan.g]

Can you tell me how far back the rubber lines run? I am at work and we have fuel line here but am unable to tell how much I need.

 

[Burning oil]

2' will be plenty. 1/4". Check at the bottom of IP there is a weep hole there. Mine leaked there very badly. Had IP rebuilt to fix it. An inspection mirror and a flashlight will help.

 

[ryan.g]

Leroy,

I have used a flashlight to see if I can find any visible leaks whatsoever. I can't find anything which is crazy because of the amount of fuel I'm losing. I looked at the return and feed lines, nothing. Checked the lines going to the injector pump and injector lines (best that I could). I can't see anything dripping, spraying, or anything. I noticed that the fuel is coming from the drivers side rear of the engine. It has completely soaked the underside of my truck. Also, what is that little T-handle valve that is coming from the filter housing? Is it just a water drain? When opened, it killed my truck. Are both ends of the hose supposed to be connected somewhere?

Sorry for being such a nuisance with my first few post. I am just lost.

 

[Burning oil]

It has to be coming from somewhere in the area. Only a few sources for it, FFM orings, hoses, IP, injector lines. I have nitrile orings for the FFM for $4. Hose you can get cheap localy. One other potential leak may be at the hose transition from hard lines to FFM. (those short hoses behind FFM) one is 3/8" one is 5/16" hose maybe 5" long.
At worst case you can remove intake and fire up the engine to see better where leaks come from.
Be sure nothing can be sucked into the heads if you do that. I vacuum the ports and surrounding area first. Thats how I found the leaky IP weep hole along with a mirror and light.

 

[Burning oil]

Another thing. If you truck dies by opening the drain on FFM then you have a problem. The ops may not be working/sending 12V to LP or the LP is dead. Both are very common problems.
The tee valve is just a drain.

 

[jrsavoie]

With the truck running test for voltage at the lift pump.

Having voltage there doesn't necessarily mean you have a good Oil Pressure Switch. The OPS can be bad, send out 12 volts but not enough amps too run the lift pump.

Check to see if there is a lift pump fuse on the passenger side firewall. There is on the 1994's. You can hotwire the lift pump there by running a jumper from one of the studs on the firewall to the fuseholder. Works for priming the fuel system after opening it up. Make sure you get the side that goes to the lift pump.

You can also test for 12 volts at the fuse holder when the truck is running.

You can also run 12 volts directly to the lift pump. Take a can of oil with you and squirt the lines and fittings while you're there. I do every time I crawl under.

If the lift pump runs while hot wired, crack the bleeder or the drain and make sure it's pumping and not just making noise.

If your lift pump is not working, I'm guessing your leak is in the return line someplace. Otherwise it would die and probably not start.

 

[3500GMC]

Don't forget there's o-rings under the bottom cap (heater) and bottom side (water sensor) on the FFM. Sometimes they spring a leak. The fuel can drip straight down from the FFM into the 'valley drain' hole. Most engines have a tube that connects to this drain hole that exits the block on the LR around the oil cooler line area.

 

[Danish Farmer]

I am guessing too, that your leak is from where the two rubber lines behind the fuel filter housing, mounts on the metal lines going down behind the engine, to the lift pump.

 

[Turbine Doc]

The spring clamps on FFM are also suspect, as the rubber hose ages it gets hard and sping clamps do not have strenght to compress hard rubber, so my recommendation, remove FFM replace the hosees (2) one feeds the IP & the oter smaller one goes to drain, also the inlet side of FFM from the lift pump also as old as other 2 and probably as near hardness. Remeber line being replaced needs to be Diesel compatable, replace spring clamps with wormscrew style ones that will not lose tension as they age.

Trick for replacing line under intake, puit a piece of heavy string like mason's line, or wire on one end FFM or IP tape/tie to end then as you pull out old hose string/wire goes with it, that you can use to pull new line back thru & under the intake.

 

[midniteplowboyy]

He's got a 93 Doc, but that trick works good with the 94up trucks, I just use a hose splice to drag the new hose through as the old comes out.

Best to just pull the intake unless you wanna relocate the fuel filter, the IP feed line is just to short to get any slack to work in there. Cut the IP feed line exactly the same length as the old one, if your too long it will kink, too short it might pull off when the fuel filter is bolted back to the intake. The intake is easy to remove, hardest part is keeping everything clean.

 

[ryan.g]

I finally got the time to pull the intake. I noticed that the metal return line had a tiny hole wore into it from rubbing the clamp on the injection lines. Could I run an all new rubber line over the intake and down to the metal lines under the truck to make future repairs a little easier? Also, I noticed that the FFM O ring on the heater has went bad. Does auto stores around here carry those o rings? Also, where the wires come out of the heater part of the FFM, I broke the little black plastic piece that seals that hole off in two pieces. Will fuel leak around those wires or not?

Also, while working on the fuel line issue, I believe I discovered the battery draining issue as well. I believe the hot wire from the passenger battery to the starter has a bad place in it. I heard a lot of sparking and then some smoke rose up into the engine compartment. I'm assuming this is what is causing the batteries to drain over time. What do you all think? Is there some other type of common electrical issue on this side of the engine I should inspect?

Thanks for the help guys! On a side note, hope everyone enjoyed their Christmas!