New Mexico Newbie

[Edgeofthewoods]

Evening folks. Just bought a 1983 GMC G2500 van, set up for camping. Not a bad deal at 1000 buck. First GM Diesel I have ever owned. Hopefully she lives up to the stories of the long life of the 6.2 series. She does need a little work, the previous owner seemd to take pretty good care of it. Kind of low on power, but I knew that. If I can get 20 mpg I will be happy. My f250 with a 460 gets 11-12 so almost double would be good. Only issue and I'll search the forums is that 1: hard shift from 1st to 2nd. and 2: she misses a bit toward the top of the power band. I need to install a tach to keep it in the sweet spot.

Chuck

Edgewood NM Territory
Enemies may come into our country and times will have changed, but then the boys will come down from the old high hills and belt on their guns again.
Louis L'Amour

[More Power]

Welcome to the board!

This van likely has the TH400 3-speed automatic transmission, which requires a working vacuum pump and VRV (Vacuum Regulator Valve - mounted onto the side of the fuel injection pump) to simulate manifold vacuum and manage shift quality in the transmission.

Jim

[Edgeofthewoods]

Welcome to the board!

This van likely has the TH400 3-speed automatic transmission, which requires a working vacuum pump and VRV (Vacuum Regulator Valve - mounted onto the side of the fuel injection pump) to simulate manifold vacuum and manage shift quality in the transmission.

Jim

Thanks for the welcome. She has a 4speed automatic. I think it is termed a 700R4. Sorry been a Ford guy for 30 + year. First GM I've owned so just now learning GM terms.:) Going to be busy searching the forums for tips and trick on this old diesel.

Chuck

[AVM62]

Welcome, I also have a 83 Diesel van, mine is a G-3500 23' camper.

[Robyn]

700R4 is the 1/2 ton auto 4 speed tranny used in these trucks.

If the trans has had a shift kit installed they can and do shift hard from 1-2.

Now the term "shifts hard" is all relative. If you accelerate very lightly the 1-2 shift should be around 20 MPH and should not be too brutal.

If a light throttle shift is much later than 20 and is real hard then there is probably some issues with the tranny.

I fairly agressive throttle should see the 1-2 shift at around 25-30 possibly and can be fairly harsh depending on whats been done to the box.

The 700 was one of the most troublesome trannies in modern times.

Being an 83 there is a good bet that this truck has seen at least one replacement in its life.

The early 700R's were very poor and most failed early on in their life span.
The 700 did not get sorted out well until about 86-87 and by then the aftermarket had a handle on what needed to be done to really spiff these little boxes up.

Many shift kits for the 700 offer quite a selection of mods that can be made to improve shifts and reliability.

If the tech that did the work got a little overzellous with his/her choice of calibrations these boxes can have a very brutal 1-2 shift.

How are the 2-3 the 3-4 and the lockup shifts ??

If these are all reasonable then the tranny is probably fine.

Oil color nice and red ???? if yes this is good.

The 700 has a very wide spread on the 1-2 shift and any agressive programing causes the shift to be quite abrupt.

The other reason is that the 1-2 shift is from a sprag/roller lock device to a band. Applying a band is problematic at best, too easy and the band burns up, to agressive and the shift is rough.

Hope this helps some here.

The missing could possibly be a dirty fuel filter.

I would change the filter out and see what happens.
If you are not familiar with the procedure, just ask and we can walk ya through it.


Best

Missy Robyn

[Edgeofthewoods]

Got to spend 5 minutes this morning before work with the van. Cold start is like I said before. But I should have added, the AM temp is about 15-18 deg F. And the heater is not plugged in. Now a cold start after sitting all day in the NM sun, let the glow plugs cycle twice turn key and with in 1-3 seconds she is running. No lope and not very loud. Infact it sounds like my neighbors 7.3 NA. So here is my game plan for the weekend. Check injecters. 2 check EGR and air filter. 3. Check timing chain. My reasoning is that I don't think the injecters where changed with the pump. And the spray pattern could be a stream instead of a mist. EGR and filters could be causing over richness. When I run it unloaded at a steady speed it seems to me it is not a misfire but it is wandering. Kind of like the ignition timing of a gasser with a bad distributor. So I am going to check the timing chain slack. Personally I am trying to avoid a new IP pump. Diesel Motive in Albuquerque wants 300 to check it out and according to them anywhere from 500 to 1500 for a reman pump. The tranny is like you said. If I am easy on it shifts easy from 1-2nd. No compression braking like a gasser when I let off the throttle. So that is my game plan for this weekend.

Thanks for all your help with this old oil burner.

Chuck Hudson