'89 GW help with possible Tranny Issue

MReno · Post by **MReno** » Wed Mar 25, 2020 5:58 am

So I have been working on my GW and find that when I shift from Park to Reverse or Drive, it does not seem as though the tranny engages properly, as it requires a moderate amount of acceleration for the vehicle to move in either direction and when doing so, it seems as thought the engine bogs down a bit. Any idea where I should begin to diagnose this?

When I first got the GW, I immediately changed the trans filter and fluid, but that is all as it relates to the tranny.

Thanks.

Post by **Stuka** » Wed Mar 25, 2020 6:47 am

I am quite sure you have done this, but have to ask. With the Jeep sitting in Neutral (NOT park) with engine running, the trans fluid reads full? I only ask because what you describe can be attributed to low fluid.

The next thing I would think is a plugged filter, but you replaced that.

will e · Post by **will e** » Wed Mar 25, 2020 7:02 am

When you engage it in drive or reverse can you 'feel' it engage? Does the engine slow down a bit?

Are you driving it around? Another thing to check... parking brake on?

Post by **fulsizjeep** » Wed Mar 25, 2020 9:24 am

Stuka wrote: ↑Wed Mar 25, 2020 6:47 amWith the Jeep sitting in Neutral (NOT park) with engine running, the trans fluid reads full? I only ask because what you describe can be attributed to low fluid.

Good point. On 727s, the fluid pump is not running in Park like a T400 is. When I have had low fluid issues with a 727, many times a pint low is in the go/no go zone. It may start out feeling ok and the first curve I go into it starts slipping.

When you changed the fluid, was there much metal flake or other junk in the fluid?

MReno · Post by **MReno** » Wed Mar 25, 2020 12:21 pm

So a couple of things: 1) I'll check to be sure the fluid in properly filled with the engine running and in N; 2) the parking brake light on the dash is on, but the emergency brake pedal is retracted (forward), so I suspect this is just an electrical issue; 3) When shifted into P or D, there is no distinct indication the vehicle tranny has engaged into gear, but when accelerator is depressed the vehicles moves; 4) I was hoping to begin to drive it around, but honestly, just got the engine up and running recently, but its definitely not running smooth (stalls frequently when at idle). Also, when depressing accelerator to about 1,000rpm, the is a bunch of popping and crackling what is coming from the exhaust (4bbl, two pipe mod by PO).

MReno · Post by **MReno** » Wed Mar 25, 2020 12:23 pm

Also, to support #2 in post above,. I recently rebuild both rear brake drum assemblies, and both tires generally spin free, indicating parking brake is not on.

Post by **Stuka** » Wed Mar 25, 2020 12:39 pm

If you are getting pops and such, sounds like the timing is way off, or perhaps too lean.

Not hearing the engine change when you shift also makes me think low fluid. As it means there is no load being put on the engine.

sirrus · Post by **sirrus** » Wed Mar 25, 2020 6:15 pm

MReno wrote:Also, to support #2 in post above,. I recently rebuild both rear brake drum assemblies, and both tires generally spin free, indicating parking brake is not on.

That light can also be turned on by loss of pressure in proportioning valve. Sometimes it’s still on even after you’ve bled the brakes - in that case really good stomp on brake pedal helps to reset it

MReno · Post by **MReno** » Thu Mar 26, 2020 6:14 am

Well, well, well don't I feel like an idiot....I should have checked the tranny fluid level a few times after replacing the filter and refilling and then of course running the engine and shifting thru all gears. I only recently got the jeep running (rough, but running), therefore I was unable to really run in through all gears, the check fluid level at idle and in N. Seems to shift into and out of gear fine, and moves forward and back (I have in in my garage currently, since its not registered yet. Hopefully will be able to get it over to my farm soon so I can see how she performs on trails.

The rough running issue (particularly at idle is what I need to address now). After several attempts to choke and start the engine, using starter fluid, I can get it running, but it is a PIA, so something else is a miss. I located TDC, changed rotor and distributor cap, and checked firing order and plug wires, and all seems normal. Not sure what else is going on....

Thanks all for your guidance. Sometimes its the simple things that are over looked!

will e · Post by **will e** » Thu Mar 26, 2020 7:31 am

Good for you.

Check for vacuum leaks. Also for weak fuel pressure (have you changed the fuel filter)?

MReno · Post by **MReno** » Thu Mar 26, 2020 9:55 am

I have changed the fuel filter (one above engine). With regards to checking for vacuum leaks, this is what I need to learn to do next, however I need to be able to first get the engine running at a low idle so it can warm up to begin to do the checks. I have a new vacuum gauge, but need to learn how to use it to diagnose engine issues.

Post by **Stuka** » Thu Mar 26, 2020 11:12 am

MReno wrote: ↑Thu Mar 26, 2020 9:55 am I have changed the fuel filter (one above engine). With regards to checking for vacuum leaks, this is what I need to learn to do next, however I need to be able to first get the engine running at a low idle so it can warm up to begin to do the checks. I have a new vacuum gauge, but need to learn how to use it to diagnose engine issues.

For vacuum leaks, first check to see if any vacuum lines are visibly cracked, or unplugged. You can do this with the engine off.

If you get it running, even if you have the idle set high for this test, use a flammable fluid (such as starting fluid, or brake clean), and spray it around any vacuum line connections, around the base of the carb, etc. If the idle goes up, you found your leak.

MReno · Post by **MReno** » Fri Mar 27, 2020 5:20 am

Great tip Stuka. Thank you.

MReno · Post by **MReno** » Fri Mar 27, 2020 7:59 am

When conducting a vacuum test of the engine, where is it suggested that I connect my vacuum gauge to on the manifold? I I have an open port (currently capped) that when the engine is running, is sucking air in thru this port. Should I connect my gauge to that port?

Lincoln7 · Post by **Lincoln7** » Sat Mar 28, 2020 2:25 am

MReno wrote: ↑Fri Mar 27, 2020 7:59 am When conducting a vacuum test of the engine, where is it suggested that I connect my vacuum gauge to on the manifold? I I have an open port (currently capped) that when the engine is running, is sucking air in thru this port. Should I connect my gauge to that port?

That should work just fine. Look for around 17-22" of vacuum at idle.

A simple method for finding vacuum leaks is to spray something flammable like brake cleaner, starter spray, WD-40, etc in areas on the engine. If idle speed changes, your leak is in that area.

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