So I recently came into posession of my late uncle's 2000 Jimmy. 4-door, "Diamond Edition." 54,000 miles!

The bad part : it has been sitting for *years*. The body is fairly solid, though it did suffer some damage in the 2018 hurricanes (broken pass. side vent window, and Something got thrown into the drivers door, denting it badly.

It also didn't run. Crank, no start, but would run briefly on starter fluid.

Issue #1 : a bad fuel pump as there was no fuel pressure. Dropped the tank & replaced the pump. Still no start. Fuel pressure at the fuel filter outlet was solid and held but bled off quickly then tested at the valve in the engine compartment.

Issue #2 : leaking fuel pressure regulator. Yay!

Just finished replacing the old spider with the new multiport type this morning. Got it all put back together, retested the fuel pressure in the engine compartment (solid!)... and it fired right up!

Issue #3 : Dex-cool sludge. At some point someone introduced green into orange. I could see that an attempt was made at some point to flush it out (what's that brand-new coolant reservoir bottle doing there?), but the stuff looking back at me out of the thermostat housing was pretty crusty.

Decided to do a bucket-flush. Sump pump hooked to the radiator inlet and dropped into a 5-gallon bucket of water, engine water outlet extended into the same bucket. Switched the pump on - clean water went in, vile stuff came out. I let it cycle for about 10 minutes then swapped swapped in a fresh bucket of water. Switched on the pump again and heard a muffled pop! and a hiss from somewhere at the back of the engine... looked underneath and oh look its leaking transmission fluid like crazy. Shut the pump off and the leak stopped, switched it on and the leak resumed.

It did not immediately seem like there was water in either the oil or trans fluid. That was this morning though - I will check them again once I get home from work.

TF did I do? Any ideas?

 

The only thing I can think of is that maybe the transmission cooler in the radiator is leaking and you're filling the transmission up with coolant, causing transmission fluid to come out the top vent.

Should be pretty easy to check by pulling the dipstick.

 

Checked it when I got home and yes there is coolant in the transmission. Looks like I'm replacing the radiator and dropping the trans fluid pan.

Is there a guide to the recommended procedure somewhere for either (or both) of these jobs? Dropping the pan looks to be a nasty job, there's just no room to work under there..

 

I don't have an automatic transmission, so I don't know for sure, but I think you have to support the back of the transmission and remove the crossmember to get the pan off.

 

You can get the pan off without taking the cross member off but I managed to cross thread one of the bolts when reinstalling the pan. I couldn't quite get it aligned when I started it because of the crossmember. Because you only get some of the fluid out when you drop the pan, I now take it to a shop to do the filter and fluid replacement. But since you got some coolant in the transmission, it would likely be good to get as much out as possible now by dropping the pan even if you take it to a shop to have a proper flush done.

 

Your going to need more than one ATF change to clear things up.

George

 

The trans pan will come off a 2000 without dropping the crossmember...but barely...and it makes a mess! Drop the pan towards the rear and let whatever fluid comes out, but then the pan has to shift a bit forward and it is full so it spills...making a mess. Since you will need to do at least two changes....install one of those drain plugs in the pan. Easy to do. Have had one installed for five years, no leaks.

 

Look like that's the case. I decided to loosen the pan enough to drain out the majority of the coolant. I also had the (new!) issue of the entire cooling system now containing a mixture of water, gelled antifreeze and emulsified ATF. Bypassed the radiator and was able to flush the engine as well as can be done without it running.

I want to do a thorough flush of the transmission next, but have to wait on the new radiator to arrive...

 

Every time the subject of transmission servicing comes up, I suggest a Fluid Evacuator, and this time is no different.

Seriously, this thing makes the job super easy by sucking almost all the fluid out the dipstick tube before you drop the pan. Works great for sucking coolant out of radiators and about a thousand other things, too. I even use mine for bleeding brakes.

 

The fluid evacuator was a good suggestion. Had one in my Amazon cart but found one of these https://www.homedepot.com/p/Lumax-Mu...1345/302544982 in Home Depot on clearance for $7. Worked perfectly to suck out the remaining fluid from the transmission. Hardly spilled anything when I dropped the pan.

(anyone know the name of the GM engineer that thought it was a good idea to stick that one 10mm bolt in the perfect spot so you can't get at it with a ratchet?)

Anyway. This past Saturday I installed the new radiator, replaced the upper and lower radiator hoses, refilled the cooling system. I then dropped the transmission pan, cleaned it out, reinstalled it with a new gasket. Refilled the pan with 5 qts of Dexron. Did an oil change + a new filter then called it for the night.

The next morning I detached the transmission return line, extended it and directed it into a bucket. Fired the truck up. I then kept on pouring quart after quart of ATF down the filler tube till the stuff coming out ran clear. Shut the truck off. Reconnected the transmission return line then went to restart it...

no crank, no start.

What.

the only variable here was that it rained *hard* on Saturday night and Sunday morning. The truck is parked in the carport and is mostly covered, but because of the direction it faces I have a pop-up tent providing shade from the afternoon sun covering most of the engine bay. The hood was up. The engine itself was dry; the only areas that got wet at all were the at extreme rear corners of the engine bay where water dripped off the tent above onto the open hood and ran down.

The start relay was slicking but nothing else. Assumed that it was just bad luck and just happened to have sopped the starter at a corroded spot - it has been sitting for some time before I started wotking on it!

That night I picked up a starter/solenoid. Got home late. decided to do the install the next day. Gave the key a twist just in case...

it cranked! Still no start.

OK then.

The next morning I gave the key a twist ... it cranked, still no start.

Closed the hood, went to the office.

Got home last night . Twisted the key and hey! it fired right up. Idled like a champ, nice and smooth. Hooked up a code reader - no codes. The fuel trim showed evidence of a vacuum leak which I quickly found and plugged. Those hosed are in bad shape, will be replacing those next.

I cannot figure out the sudden no-crank-no-start -> crank-no-start -> crank-start issue though. Is there some single component which could provoke this behavior by getting wet?