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94 Yukon won't shift


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JP Crazy
Novice

Oct 27, 2012, 4:45 PM

Post #1 of 17 (2692 views)
  post locked   94 Yukon won't shift  

I have a 94 GMC Yukon sle 5.7L with 232000 miles, the other day needed to clean motor to find power steering leak and decided to do the whole engine bay, sprayed it down with a spray can of stuff that smelled like diesel fuel the pressure washed everywhere including firewall, backed it into the garage, next morning it would not start, (I got something wet) after a few days of letting dry out and still not starting I shot a little either in the throttle body and it started and then decided to drive it around the block to help dry it out, I ran the truck hard ( foot into it ) to speed the drying process, by the time I got home I noticed that it was not shifting properly, thought something still needed to dry out, tried it two days later and the trans would not shift up thru the gears unless I forced it (I goosed the gas at about 25 - 3000 rpm) then it would shift into 2nd and had to do the same to get to 3rd, I then replaced the MAP sensor hoping that for a few bucks I could fix the problem but that did not fix it, the fluid checks up to proper level, looks ok but might have a slight burnt smell to it. I bought the truck with 60000 miles on it and the first owner installed a after market trans cooler, the trans has never had service, flushed, or filter changed and has never leaked, (if it works don’t mess with it).
I also noticed that the engine now Idles in neutral at 1400 to 1600 rpm and used to be at around 600 – 800 not sure if this is a different problem or related to the first one?


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Oct 27, 2012, 4:57 PM

Post #2 of 17 (2678 views)
  post locked   Re: 94 Yukon won't shift  

I hope you learned something here....................
You do not pressure clean electronically controlled engines.


Quote
I bought the truck with 60000 miles on it and the first owner installed a after market trans cooler, the trans has never had service, flushed, or filter changed and has never leaked, (if it works don’t mess with it).


Oh, how wrong you are


Quote
the fluid checks up to proper level, looks ok but might have a slight burnt smell to it.


That pretty much means that you're just too late. Plan on a rebuild now and next time flush the fluid as a preventative before you have a problem.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



JP Crazy
Novice

Oct 28, 2012, 11:01 AM

Post #3 of 17 (2629 views)
  post locked   Re: 94 Yukon won't shift  

In all my Years no one until now has said do not pressure wash electronic controlled engine, and in the 12 + years of ownership I have cleaned it this way many time with no problems at all till now,

Yes, regular service on transmissions is the proper way to go. but the poor man’s way is something a little different, ”The squeaky wheel gets the grease”, I sure there is more than a few people that would be very glade to have no problems with there trans at all for 230000 miles

I guess what I was hopping for was a little more detail description of what is wrong with the trans, not enough fluid pressure, governor faulty, Computer control faulty, clutches and bands defective, not just “it’s to late, recommend rebuilt”

I believe there is still life left in this trans, I'll let you know that works out.



Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Oct 28, 2012, 11:06 AM

Post #4 of 17 (2626 views)
  post locked   Re: 94 Yukon won't shift  

If you believe that trans is still saveable, you might see some aliens before the day is out too.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Sidom
Veteran / Moderator
Sidom profile image

Oct 28, 2012, 2:24 PM

Post #5 of 17 (2614 views)
  post locked   Re: 94 Yukon won't shift  

Get a can of brake cleaner or electrical cleaner, cafefully take apart any connector you can see & clean them out......

It is a very bad idea to pressure washer engines these days. You may have not ever had a problem but I have seen problems too many times to count after someone washed an engine.....

The problem is, the connectors are sealed (very well) to keep moisture out. Once water gets in and creates problems it doesn't get out due to the connector being sealed....


JP Crazy
Novice

Oct 28, 2012, 3:26 PM

Post #6 of 17 (2607 views)
  post locked   Re: 94 Yukon won't shift  

Thank you, Thank you Very much, finally helpful information that can be useful, I just made a trip to Napa to get some parts and talked to the man there about the information, OR lack there of, I got from this web expert, and I have to say that I felt quite hot under the collar from the way he replied to my post, he must of thought that I am some guy that does not know witch end of the screwdriver to hold onto, on the contrary, I have been a professional Mechanic for over 30 years and have a Degree in applied Science, I just do not do transmissions and do not have any experience in troubleshooting them.
The guy at the parts store told me that he also pressure washed he’s 95 and had the SAME problem that I am experiencing, he said he got moisture on the computer under the dash due to a hole in the firewall and had to drive it home in first and he also said that it was FINE after it dried out, now I have checked my computer and it is bone dry so I believe at this time that my problem is where you have pointed me to, Thanks Aging, and tell the other guy that the Aliens say HI.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Oct 28, 2012, 3:54 PM

Post #7 of 17 (2603 views)
  post locked   Re: 94 Yukon won't shift  


Quote
I have been a professional Mechanic for over 30 years and have a Degree in applied Science,


Oh really? I guess you were absent the day they taught you that electrical components and water don't mix, especially under 3000PSI.

You have 230K, burnt fluid and a slipping transmission. You can clean electrical connectors until the cows come home and your not fixing that transmission without tearing it down.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Sidom
Veteran / Moderator
Sidom profile image

Oct 28, 2012, 4:52 PM

Post #8 of 17 (2599 views)
  post locked   Re: 94 Yukon won't shift  

Do what you can and you might get lucky. HT does bring up some good points about the fluid condition and mileage.

The advise given here is free and by guys in the field and donating their time and experience for free.
Don't let this thread sink to the point where the mods are being attack or it won't go well


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Oct 29, 2012, 6:56 AM

Post #9 of 17 (2585 views)
  post locked   Re: 94 Yukon won't shift  

My take: Don't wash engines period. Wipe dry anything needed. Clean by hand with rags with even Armour All if you must. Looking for leaks air blow area dry to see a leak return. No water never mind under pressure. Items off car do what you want.

Hey - all those electric connections are sealed and about all greased and washing that away if not an immediate problem will be later on vehicles tons older than this. Not some but most had problems to disasters from solvents AND pressure cleaning. This isn't a mod attack it's the truth,

T



JP Crazy
Novice

Oct 29, 2012, 5:13 PM

Post #10 of 17 (2566 views)
  post locked   Re: 94 Yukon won't shift  

Thank you Gentlemen (The last two) for you kind words of advice and not making me feel even worse for the mistake I made in washing the engine with a pressure washer, I got my mechanical education back in the 70s long before the wide spread use of pressure washers and some 10 years before the introduction of high tech electronically controlled components in the engine compartment, and on Diesel engines it was another 5 + years after automotive before they got computers to control things, Ya I missed that bulletin, I did not work at a dealership where they kept there workers well informed,

HT, Yes I have 230k but to me the fluid smells old and the trans is NOT slipping, you assumed that on your own, YES YOU may be RIGHT, the trans might well be done for, but I sure am willing to try a lot of cheep things before I shell out hundreds on a overhaul, telling me “till the cows come home” and “see aliens yet today” is not very helpful

And has no one but me see a correlation between the trans not shifting properly and the engine not Idling right? Both happening at the same time?

I sincerely apologize to any MOD that I might have offended in this or any other of my posts, I was simply try to find alternatives that might fix my problem before I head to the transmission shop.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Oct 29, 2012, 5:19 PM

Post #11 of 17 (2563 views)
  post locked   Re: 94 Yukon won't shift  


Quote
And has no one but me see a correlation between the trans not shifting properly and the engine not Idling right?


No...... but I did see the correlation between running the truck hard to try to dry it out and the transmission starting to act up.




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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Discretesignals
Ultimate Carjunky / Moderator
Discretesignals profile image

Oct 29, 2012, 7:11 PM

Post #12 of 17 (2553 views)
  post locked   Re: 94 Yukon won't shift  

Maybe you got water in the TPS or it's connector. TPS is important when it comes to shift timing/delay. Also if the TPS is shorted by the water and showing WOT, the engine won't start because the PCM will go into clear flood mode. A TPS problem could also cause a higher than normal idle. Check the TPS voltage.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Oct 29, 2012, 7:21 PM)


JP Crazy
Novice

Nov 1, 2012, 4:18 PM

Post #13 of 17 (2519 views)
  post locked   Re: 94 Yukon won't shift  

Thank you Sir for your input and your time, the more I think about it, the more I think that’s where the problem is at, but not exactly for the reason that you’ve indicated, I now have time this weekend to work on it and will let you know the out come.


JP Crazy
Novice

Nov 3, 2012, 12:40 PM

Post #14 of 17 (2480 views)
  post locked   Re: 94 Yukon won't shift  

END REPORT:

Washed engine with solvent and pressure washer: Bad Idea but allot of people will still do it, all that happened to me this time was water in the distributor cap.

Forced the engine to start by shooting Ether into the engine with air cleaner off: Another bad Idea, the ether ignited resulting in a fire for about 1 min before I could extinguish it,

Then the truck would start OK but would not Idle correct nor would the trans shift properly,

Received may Ideas for repair here from the experts, form Trans is junk, to dry out electrical connections, to check TPS, then I remembered the fire witch I had not thought much of, removed the TPS and discovered damage to the unit due to the fire,

Replaced the TPS unit and all system are working properly, the engine is Idling right and the trans is shifting as it should.

I would like to thank the Experts for there input and for there time helping me with this problem that I brought upon myself with less than ideal judgment.

To: Sidom and Tom Greenleaf, I Sincerely Thank you two for your help and Advice

To: Discretesignals, I Sincerely Thank you as well for your “Hitting the nail in the head” with your Advice

Removed last comment in lieu of banning.


(This post was edited by Hammer Time on Nov 4, 2012, 3:18 PM)


Discretesignals
Ultimate Carjunky / Moderator
Discretesignals profile image

Nov 3, 2012, 3:24 PM

Post #15 of 17 (2475 views)
  post locked   Re: 94 Yukon won't shift  

I don't think that your alone on that. I believe that every mechanic/tech is going to experience the wrath from the fire gods in their career.

So far to date:

Flame licked by the fire gods from two carb backfires.

Two engine compartment fires due to brake cleaner igniting on a hot engine parts.

Extinguished an engine fire due to cranking an engine with the plugs out. Fuel vapor ignited as it was pushed out the spark plug hole across a plug wire arching to the engine block.

Almost burned a friends garage down because he was washing parts in gasoline and I was on the other side of the garage using a torch. The vapor trail happened to reach were I was and a nice blue carpet flame traveled 20ft to the pan of gasoline.

Had a tow vehicle's battery cable short to the frame and ignite while sitting in the parking lot. Nothing like a butt puckering Chinese fire drill.

All I have to say is, Thank you Jesus for having a fire extinguisher near by during all those situations."

Anyone hiring?? LOL





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.


JP Crazy
Novice

Nov 4, 2012, 2:20 PM

Post #16 of 17 (2453 views)
  post locked   Re: 94 Yukon won't shift  

Amen Brother, play with fire and you will get burned, Work with fire and you need to keep that extinguisher handy,

Had carb off and plugs, through plug wires on top of engine, was checking fuel pump volume, the force of the fuel blew the plastic pop bottle off and sprayed the top of engine with fuel and the spark plug wires sparked to ground, had to white dust the engine that time,

Just old enough to mow lawns, in a big hurry, was transferring gas from a full 5 gal to a 2 gal can, could not find funnel, and my aim was not that good, was standing in a 5 foot ring of spilled gas when the water heater around the corner transformed the spilled gas into a column of flame the same size to the ceiling, about 3 milla seconds later I jump about 10 feet away with not a single singe, attached garage, the house was totaled.

And I to believe that I have said those words “ Am I missing an eye brow?” at one time or another later in life,

Good Luck in that job search, LOLOLOLOLOLOL


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Nov 4, 2012, 3:20 PM

Post #17 of 17 (2444 views)
  post locked   Re: 94 Yukon won't shift  

LOL............... a real genius at work.

This thread has run it's course and is ending now.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.







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