1994 4T60 delayed engagment?

[rich_e777]

Not sure if this follows my manuals definition of delayed engagement for my transmission. Awhile back I replaced the neutral safety switch and then the starter and right about the time I took the switch off to clean and readjust it before replacing it I noticed that after starting it up and putting it in R or D it would act as if in N. I could feel the shift linkage move but the lurch from going from P to R or D would not present itself until after the engine ran for a few seconds(build up pressure?) then the trans would pick up on what the linkage was telling it to do.

 

Fluid level is and should be OK, however even further back I replaced both the trans cooler lines at the same time and there is a 50% chance I have them backwards, In my mind if they were backwards something catastrophic would have happened by now but I've never reversed the flow of fluid to the transmission so I don't know what it would do. Before going any further the fluid is still red, unburned and the filter and fluid are WAY less than 15,000 miles. A small leak is present at one of the rubber to metal joints of the trans cooler line even after switching to the ring/screw style clamp vs the POS ones you have to use pliers on. Which leads me to think maybe I did get those lines backwards but surely I`d be seeing a massive amount of trans fluid on the ground or in the coolant if they were.

 

Has anyone come across this issue or something similar before and what was done to remedy the problem? The manual has me thinking of the most complicated solution to the most complicated problem and that has very seldom been the case, always something simple that someone here thought of that I didn't (Long Island teas are my current drink of choice and forget they can sneak up on the unsuspecting) which is why this thread exists now.

[RobertISaar]

that would be delayed engagement.

 

what happens if you pull the vacuum line off of the modulator and then shift into gear? should grab quite hard with no vacuum going to it.

[Euro]

My Lumina did that right after I had a fluid/filter change on the trans. I threw almost an entire bottle of Lucas in it, and it worked perfectly the rest of my ownership. If I wasn't just a dumb HS kid, I probably would've tried to investigate..but ya know

[rich_e777]

that would be delayed engagement.

 

what happens if you pull the vacuum line off of the modulator and then shift into gear? should grab quite hard with no vacuum going to it.

 

Will let you know first thing in the morning. If removing the vacuum line from the modulator and it doesn't have any effect on the situation, what would that indicate?

Im thinking I messed something up tightening down the neutral switch bolt.

Edited May 2, 2014 by rich_e777

[55trucker]

Hmmmmm.........when you reinstalled the safety switch did you realign the locator notches to ensure that the electrical contacts are in their proper position with respect to the ECM *seeing* the trans in the gear selected?

[Schurkey]

Awhile back I replaced the neutral safety switch and then the starter and right about the time I took the switch off to clean and readjust it before replacing it I noticed that after starting it up and putting it in R or D it would act as if in N. I could feel the shift linkage move but the lurch from going from P to R or D would not present itself until after the engine ran for a few seconds(build up pressure?) then the trans would pick up on what the linkage was telling it to do.

I'm not clear--did the transmission engagement problem happen directly after the work you did, or did it act up "about" the same time?

 

Fluid level is and should be OK,

Have you checked it recently?

 

however even further back I replaced both the trans cooler lines at the same time and there is a 50% chance I have them backwards, In my mind if they were backwards something catastrophic would have happened by now but I've never reversed the flow of fluid to the transmission

Reversing the fluid connections at the cooler reverses the flow of fluid through the cooler, but not the flow of fluid to the transmission.

 

maybe I did get those lines backwards but surely I`d be seeing a massive amount of trans fluid on the ground or in the coolant if they were.

Reversing the coolant flow won't cause leaks of ATF or coolant. It might dislodge crap trapped in the cooler, which means that it either gets re-trapped in the cooler, or it makes it's way into the transmission. The cooler will also lose some efficiency, so the fluid won't be cooled as well.

[rich_e777]

Hmmmmm.........when you reinstalled the safety switch did you realign the locator notches to ensure that the electrical contacts are in their proper position with respect to the ECM *seeing* the trans in the gear selected?

 

 

 

Yes, followed instruction exactly. If it was not adjusted then it would start in all kinds of gears depending on how far out of whack the thing is, the new one had a more defined notch and when the trans is in neutral every thing lines up perfectly when you slide the switch down on the trans.

Edited May 2, 2014 by rich_e777

[rich_e777]

I'm not clear--did the transmission engagement problem happen directly after the work you did, or did it act up "about" the same time?

 

 

Have you checked it recently?

 

 

Reversing the fluid connections at the cooler reverses the flow of fluid through the cooler, but not the flow of fluid to the transmission.

 

 

Reversing the coolant flow won't cause leaks of ATF or coolant. It might dislodge crap trapped in the cooler, which means that it either gets re-trapped in the cooler, or it makes it's way into the transmission. The cooler will also lose some efficiency, so the fluid won't be cooled as well.

 

Sorry, situation started about 3 weeks ago when I had a no start no crank scenario when I suspected that my factory neutral switch I had finally failed, the plastic ring on the trans was cracked and the hole was rounded off to the point it didn't grab the transmission good, replaced with brand new one properly adjusted, then had to replaced starter as N switch was only part off that issue. Both did need replacing, that is when the current issue arose. I checked the fluid level after a warm up drive, it was low and had to add two quarts to bring it back to the right level. One of the line was leaking at the rubber to metal joint and I have a ring clamp on it now. Before that it probably had been 2 months since I checked it before that.

 

Once on the road and moving I have no issues shifting, it maybe getting a bit harsh from 1st to 2nd but nothing else that I can tell.

 

My trans cooler lines were replaced with my radiator at least a years ago and like an idiot I took both off to make sure I got the right length/size of hose, when I went to put the new hose back on I went with the trans schematics in my manual to determine the flow and not once do the hoses cross so I`m pretty sure I got it right but wanted to bring up the possibility.

[rich_e777]

that would be delayed engagement.

 

what happens if you pull the vacuum line off of the modulator and then shift into gear? should grab quite hard with no vacuum going to it.

 

Yeah it shifted hard but engaged, did it twice, re connected modulator restarted engine and it shifted ok, like it normally does with no issues. The modulator is not that old, about 2 years. No oil was in the line.

[RobertISaar]

sounds like the modulator is doing its job then..... or at least well enough. i was wondering if it were somehow jammed into a low-line pressure position, causing a slow accumulator fill/shift.

[rich_e777]

Conditions for delayed engagement per manual are

 

low fluid level

Cooler checkball not seated allowing converter drain back

reverse servo assembly seal damaged

input shaft and housing assembly- damaged retainer and ball

forward servo assemble- two different potential seals damaged

damaged clutch outer piston seal damaged

 

Im trying to work my way through the manual but without the required diagnostic equipment the manual assumes you have it makes it slightly difficult. Any nifty way of testing any of the above im all ears. I will also see about doing a pressure test on the trans maybe Sunday.

 

 

Thanks for the replies.

[Schurkey]

I checked the fluid level after a warm up drive, it was low and had to add two quarts to bring it back to the right level. One of the line was leaking at the rubber to metal joint and I have a ring clamp on it now. Before that it probably had been 2 months since I checked it before that.

 

Once on the road and moving I have no issues shifting, it maybe getting a bit harsh from 1st to 2nd but nothing else that I can tell.

 

Conditions for delayed engagement per manual are

 

low fluid level

Cooler checkball not seated allowing converter drain back

reverse servo assembly seal damaged

input shaft and housing assembly- damaged retainer and ball

forward servo assemble- two different potential seals damaged

damaged clutch outer piston seal damaged

 

Im trying to work my way through the manual but without the required diagnostic equipment the manual assumes you have it makes it slightly difficult. Any nifty way of testing any of the above im all ears. I will also see about doing a pressure test on the trans maybe Sunday.

 

 

Thanks for the replies.

Two quarts low on fluid, and harsh shifting?

 

FIRST thing I'd suspect is a defective modulator. You've said there's no oil in the tubing, but you'd do well to check again.

[rich_e777]

Sort of forgot about this one, went ahead and swapped modulators and reduced the length of hose by getting the metal line down between the engine mount bracket and under the metal coolant line running across the front of the engine. Also got a 90 degree elbow of stiffer hose vs the cut to length stuff that kinks as it bends at the modulator end. The old one was full of trans fluid.

 

I might have to put the manual away for awhile, I`m like a hypochondriac on WebMD about my baby.

[rich_e777]

Problem presented itself again, this time I didn't have to shift out of reverse but the gear caught on the rev down. Could this be a failing torque converter?

[Schurkey]

Unlikely to be a failed torque converter. Did you ever re-fill the trans fluid after changing to a good modulator?

 

Are you sure the replacement modulator is any better than the leaking original?

[rich_e777]

Unlikely to be a failed torque converter. Did you ever re-fill the trans fluid after changing to a good modulator?

 

Are you sure the replacement modulator is any better than the leaking original?

 

Of course and I have been keeping an eye on the fluid level daily since the issue started, I would hope a new modulator wouldn`t be bad but its worth checking out. It started about the same time I replace the neutral safety switch with a new one. It only happened the one time and I have since replaced hose clamps on the cooler lines with good ones, hoses are still new I just ran out of clamps and had to re use a few factory pinch clamps instead. You think it could be air working itself out of the system?

[Schurkey]

You think it could be air working itself out of the system?

Nope. If there's air in the system, it's likely from a bad filter-to-case seal. Possible, but unlikely.

[rich_e777]

Just dropped the pan and changed fluid and filter Wednesday. There was a bit of build up on the magnet but no large chunks of metal so I guess that's some good news. After the job was done it drove and shifted fine that afternoon but the following morning it had the same issue. So I have found out that the car has to sit overnight for it to have the issue. I'm looking around for a pressure gauge to use to get some numbers as it seems to me that is a pressure/seal issue.

 

When I do find a vacuum gauge(hand operated pump style) where does it connect to on the 4T60-E?(the modulator port?) The manual isn't very clear on that. The pressure gauge appears to connect to the blow off vent on top. Also does anyone have an old school J 38791 Transmission test box for I could borrow?(for a rental charge plus I`d eat the round trip shipping charges)

[rich_e777]

So I found one of those Trans boxes after following the procedures for a trans check without a box. Its basically testing voltage and resistance in the harness while shifting gears. Transmission passed. Put a vacuum pump on the modulator and fed it 18Hgs of vacuum to the modulator(I am under the impression this is the specified vacuum measurement from the line pressure test outlined in manual) Transmission shifted fine. So stumped I thought maybe its got something to do with the vacuum supply going to the modulator. So I took a vacuum reading of the UIM modulator line and got a fluctuating(non-steady, needle just wiggles back and forth with no pattern) reading from IIRC 14Hg-19Hg, indicative of valve issues in the cylinder heads. I just changed the damn head gaskets less than a year ago and I do not remember seeing any fluid run through the valves when I cleaned them up real good.

 

When having to move the car ive been unplugging the modulator, shifting to N, reconnecting modulator and she shifts just fine after that. Don't quite understand how that happens yet. I`ll keep updating so anyone else with this issue might find the info here and will post what finally fixed the issue. I still might get a new transmission anyways just in case it my issues are internal trans and then I`ll have my current one to take apart and figure out.

[Schurkey]

I took a vacuum reading of the UIM modulator line and got a fluctuating(non-steady, needle just wiggles back and forth with no pattern) reading from IIRC 14Hg-19Hg, indicative of valve issues in the cylinder heads. I just changed the damn head gaskets less than a year ago and I do not remember seeing any fluid run through the valves when I cleaned them up real good.

A cylinder leakdown test is in order. No leakage past valves is acceptable. No leakage into cooling system is acceptable. Some leakage past rings is acceptable, but the amount needs to be appropriately small. Erratic vacuum can also be from broken valve springs. HOW DOES THE ENGINE RUN?

 

Testing valve seal by pouring fluid into the combustion chamber is primitive at best, and inaccurate at worst. If you can find a vacuum-testing rig you'll be much better off. A Mity-Vac and a fabricated plate to seal the port would work. First photo is of the compressed-air-powered (Venturi) tester with the port blocked by a suction-cup. Shows the maximum vacuum the tester can generate:

 

Second photo shows tester connected to exhaust port of LQ1. Valves are holding within about 1.5% of the maximum possible vacuum. The machinist I bought this rig from told me that 50% leakage was acceptable--but I think his spec is FAR too lax.

 

 

 

I'm also curious what you mean by "I cleaned them up real good" referring to the valves. I've pulled apart four LQ1 heads, every exhaust valve looked the same--terrible. The intake valves needed .001 machined off the faces to make them look like new; the exhausts took .003--.004. Were your valves machined or merely carbon-cleaned?

[Galaxie500XL]

Excellent write up, Schurkey...

 

I'd suspect most all of us with LQ1's with a fair bit of mileage on them has at least some degree of leakage at the exhaust valves...

[Schurkey]

Excellent write up, Schurkey...

[Elvis Voice]Thankyew, thankyew verra much.[/Elvis Voice]

 

I'd suspect most all of us with LQ1's with a fair bit of mileage on them has at least some degree of leakage at the exhaust valves...

The second pair of heads came to me in pieces; I bought them as "spare parts" and I have zero history on them. The first pair came off my '93 Lumina; about 150K miles and two damaged head-gaskets caused the tear-down. All four heads were quite similar in terms of valve, seat, and guide condition:

 

The intake valves looked to be re-usable. Not fabulous, but pretty-good. I ground them anyway because I had a new-to-me valve grinder and needed the experience. Intake and exhaust seats were similarly in decent, usable condition. The seats must be hard as hell to not be destroyed by the exhaust valves. The exhaust valves, as shown in previous post, looked horrible.

 

For what it's worth, I bought a batch of aftermarket LQ1 intake and exhaust valves at steep discount from a mail-order supplier. Measured on my valve grinder, they're not as concentric as the GM valves. We can hope the exhaust valves are made from better material, though.

[George]

Sounds like an input shaft seal (not sure what seal) is leaking a bit causing longer than usual fill times (clutch pack?). I've heard that idling for a few minutes will give it time to fill, also putting the shifter in first gear is suppose to double the line pressure allowing for faster fill times. If either of these tricks work it sounds like a rebuild is in order.

[rich_e777]

A cylinder leakdown test is in order. No leakage past valves is acceptable. No leakage into cooling system is acceptable. Some leakage past rings is acceptable, but the amount needs to be appropriately small. Erratic vacuum can also be from broken valve springs. HOW DOES THE ENGINE RUN?

 

Testing valve seal by pouring fluid into the combustion chamber is primitive at best, and inaccurate at worst. If you can find a vacuum-testing rig you'll be much better off. A Mity-Vac and a fabricated plate to seal the port would work. First photo is of the compressed-air-powered (Venturi) tester with the port blocked by a suction-cup. Shows the maximum vacuum the tester can generate:

 

Second photo shows tester connected to exhaust port of LQ1. Valves are holding within about 1.5% of the maximum possible vacuum. The machinist I bought this rig from told me that 50% leakage was acceptable--but I think his spec is FAR too lax.

 

 

 

I'm also curious what you mean by "I cleaned them up real good" referring to the valves. I've pulled apart four LQ1 heads, every exhaust valve looked the same--terrible. The intake valves needed .001 machined off the faces to make them look like new; the exhausts took .003--.004. Were your valves machined or merely carbon-cleaned?

 

Didn't get to the tops of the valves but I cleaned the exposed bottoms, I used a wire brush with somewhat softer bristles than some others. Attempted using the same brush to clean off old timing cover gasket but it wouldn't even scratch it or the engine block(had to use the stiff ones) so I thought it safe to use on the heads. The engine runs fairly smooth, a bit of a rough idle after its warmed up. There is an another symptom I thought unrelated but I`ll mention it. After driving for awhile I`ll stop at a red light and the oil pressure gauge starts fluctuating and will eventually drop to 0 setting off the check gauges light. When it sets off the light the engine tone does change. I have tested the oil pressure at idle when the cluster gauge was doing this and got spec oil pressure 8-10 psi cannot remember which at the moment. A 68(k)? Ohm inline resistor has been mentioned to be the culprit of that issue.

 

I had planned on doing a compression test this weekend and will explore leak down test options, one of those devices you have there would be awesome to have around as well.

[rich_e777]

Sounds like an input shaft seal (not sure what seal) is leaking a bit causing longer than usual fill times (clutch pack?). I've heard that idling for a few minutes will give it time to fill, also putting the shifter in first gear is suppose to double the line pressure allowing for faster fill times. If either of these tricks work it sounds like a rebuild is in order.

 

At first after shifting a few times I did wait while it was idling before it would shift, after unplugging the line and shifting it would slam into gear. I`ll try idling in first gear and see if that works. Now after it shifts for the first time its fine. I can drive it to the gas station fill it up, stuff down some BBQ and go start it right back up with no shifting issues. One of these days I will try a trans rebuild, that's when I have another for back up.