Project 99 Yukon

[My99Yukon]

If you replaced the motor with a long block (block with heads and no intake, i would suspect they used the same injectors. Check youtube for changing spider injectors. There are several videos that are very helpful.

I just checked my old invoices and you are right. They dropped in the long block 350ci and probably just reused the old injectors. I will check out the videos again but the ones that I saw seemed like it took quite a bit of disassembly to replace those. The engine does not smoke and runs smoothly. Is there any way to tell if I really need to replace the spider injectors without tearing into it?

 

[bunchz71]

I just checked my old invoices and you are right. They dropped in the long block 350ci and probably just reused the old injectors. I will check out the videos again but the ones that I saw seemed like it took quite a bit of disassembly to replace those. The engine does not smoke and runs smoothly. Is there any way to tell if I really need to replace the spider injectors without tearing into it?

Honestlu, it it runs perfect and doesnt have anybcold start issues, I wouldnt mess with it. I only replaced mine because of my faulty fuel regulator and hard start issues. It seems you were running rich by the black carbon buildup on the underside of your throttle body butterfly, its entirely your call. If you're happy with it, i wouldnt mess with it.

 

[My99Yukon]

If you replaced the motor with a long block (block with heads and no intake, i would suspect they used the same injectors. Check youtube for changing spider injectors. There are several videos that are very helpful.

You are right in your last post. The mechanic ordered and replaced the long block so I am sure he just reused the 140K old injectors because I don't see the new spider injectors on the invoice. That makes no sense but I am sure he thought he was saving me some money. How shortsighted. Knowing that, I will replace the injectors in the next few months because it does smoke a bit.

The distributor cap and rotors where changed at the time of the motor swap about 6 years ago. Would it be wise based on the age to replace those as well at the same time? I am not sure the life expectancy of this hardware. Thanks.

 

[bunchz71]

You are right in your last post. The mechanic ordered and replaced the long block so I am sure he just reused the 140K old injectors because I don't see the new spider injectors on the invoice. That makes no sense but I am sure he thought he was saving me some money. How shortsighted. Knowing that, I will replace the injectors in the next few months because it does smoke a bit.

The distributor cap and rotors where changed at the time of the motor swap about 6 years ago. Would it be wise based on the age to replace those as well at the same time? I am not sure the life expectancy of this hardware. Thanks.

If its been 6 years, i would bet its time to change them again. Just my opinion

 

[bunchz71]

Which transfer case do you have? Do you have the auto pushbutton four-wheel-drive or the manual lever? My transfer case is the NP 246 and it has the pushbutton auto four-wheel-drive. If you have the two for six transfer case do not use any oil's in there except the AC Delco brand from GM. It should be blue in color. I am in the process of rebuilding mine right now because I use the stuff from AutoZone that said it was safe for auto trak II and it wasn't. I changed mine about 10 or 15,000 miles ago and when I drained it out it look like 90 weight. It was definitely the wrong fluid because it smoked all of my clutches in my auto for Drive have assembly.

 

[My99Yukon]

I have the NP 246 and with the pushbutton auto four-wheel-drive. I was troubleshooting my 4 lo and replaced the push button interface, TCase motor, changed fluid and I am left scratching my head because it won't drop into 4Lo. I had it rebuilt and it was just out of the 12 mo warranty when I discovered the fault.

I used autotrak II when I flushed/filled and I believe the fluid looked pretty good when I drained it. I have had a complete electrical diagnostic and all appears to function normally but I hear three "chunks" like metal hitting metal and it drops back into the previous selection. 4H, 2H and auto works fine.

After my last diagnostic, I think I will have to crack the case and see if a ring slipped or something that is blocking the mechanism.

I have never done that nor do I have any transmission type experience so I might have to hand this off to a shop. I will do some more youtube research and see if I think I am capable of pulling it apart and putting it back together without breaking something or forgetting how it should be reassembled.

While we are on a similar topic, I am considering regearing from 3.42 to 4.10 to accomodate my bigger tires. It seems like adjusting some of the tolerances can be tricky. Is this something that you would probably encourage someone to just let a shop handle?

 

[My99Yukon]

Which transfer case do you have? Do you have the auto pushbutton four-wheel-drive or the manual lever? My transfer case is the NP 246 and it has the pushbutton auto four-wheel-drive. If you have the two for six transfer case do not use any oil's in there except the AC Delco brand from GM. It should be blue in color. I am in the process of rebuilding mine right now because I use the stuff from AutoZone that said it was safe for auto trak II and it wasn't. I changed mine about 10 or 15,000 miles ago and when I drained it out it look like 90 weight. It was definitely the wrong fluid because it smoked all of my clutches in my auto for Drive have assembly.

I dont think I replied to your last post but rather just posted a response so please see above. Also, when I replace the distributor cap and rotors, what do you think about replacing the items with something like
MSD Ignition 5592 Street Fire Distributor for GM Vortec V8 Engine
: https://www.amazon.com/MSD-Ignition...440-9-2-145-90-1-0&sr=1-14&ymm=1999:gmc:yukon

 

[bunchz71]

Honestly, I think its overkill... I mean you only have a stock motor. I would go back with OEM, like the one I did. It works fine with no issues, plus the distributor clamp makes the timing not adjustable. When you have #1 cylinder TDC and the timing mark lined up on balancer, you put the distributor in pointing to #1 cylinder on the cap (not where the spark plug wire on the distributor cap is, but where the point is. With the cap on, I put a mark on the distrubutor housing. Line up the rotor to the timing mark you put on the housing and when your distributor hold down lines up with the hole bolt hole on your motor, you know you are perfect on your timing. With the clamps that are loose and make the timing adjustable, it is harder to get the timing right, and you more and likely will need a OBD II diagnostic scanner that reads cam retard.

Just my two cents. Save that money for some thing else for your ride.

https://www.amazon.com/gp/product/B006CUWF8C/ref=oh_aui_detailpage_o07_s00?ie=UTF8&psc=1

https://www.amazon.com/ACDelco-217-...rd_wg=xHZ6Z&psc=1&refRID=ZE2DV0G5EM5G60PR0CQ0

https://www.amazon.com/Fel-Pro-MS90...rd_wg=KTkN8&psc=1&refRID=ZRFS126B8Z51NXCCHEQR

 

[bunchz71]

I have the NP 246 and with the pushbutton auto four-wheel-drive. I was troubleshooting my 4 lo and replaced the push button interface, TCase motor, changed fluid and I am left scratching my head because it won't drop into 4Lo. I had it rebuilt and it was just out of the 12 mo warranty when I discovered the fault.

I used autotrak II when I flushed/filled and I believe the fluid looked pretty good when I drained it. I have had a complete electrical diagnostic and all appears to function normally but I hear three "chunks" like metal hitting metal and it drops back into the previous selection. 4H, 2H and auto works fine.

After my last diagnostic, I think I will have to crack the case and see if a ring slipped or something that is blocking the mechanism.

I have never done that nor do I have any transmission type experience so I might have to hand this off to a shop. I will do some more youtube research and see if I think I am capable of pulling it apart and putting it back together without breaking something or forgetting how it should be reassembled.

While we are on a similar topic, I am considering regearing from 3.42 to 4.10 to accomodate my bigger tires. It seems like adjusting some of the tolerances can be tricky. Is this something that you would probably encourage someone to just let a shop handle?

Just a silly question, but are you stopped with the vehicle in neutral with foot on brake when you try 4 LO ?

 

[bunchz71]

I have the NP 246 and with the pushbutton auto four-wheel-drive. I was troubleshooting my 4 lo and replaced the push button interface, TCase motor, changed fluid and I am left scratching my head because it won't drop into 4Lo. I had it rebuilt and it was just out of the 12 mo warranty when I discovered the fault.

I used autotrak II when I flushed/filled and I believe the fluid looked pretty good when I drained it. I have had a complete electrical diagnostic and all appears to function normally but I hear three "chunks" like metal hitting metal and it drops back into the previous selection. 4H, 2H and auto works fine.

After my last diagnostic, I think I will have to crack the case and see if a ring slipped or something that is blocking the mechanism.

I have never done that nor do I have any transmission type experience so I might have to hand this off to a shop. I will do some more youtube research and see if I think I am capable of pulling it apart and putting it back together without breaking something or forgetting how it should be reassembled.

While we are on a similar topic, I am considering regearing from 3.42 to 4.10 to accomodate my bigger tires. It seems like adjusting some of the tolerances can be tricky. Is this something that you would probably encourage someone to just let a shop handle?

Try these links from RICKAFIX on youtube. They are pretty informative and these are what I went by when I did mine. It shows it from the start to finish.