I fixed it on mine. I figured there was nothing to loose since the part was on a 5 month backorder. I posted on a couple forums here’s the full story below.
I successfully repaired my coolant control valve at home, no dealer fees, or WAITING for spare parts required…My 21 Sierra started throwing the P1098 code at 63k miles and blasting fans at 100% power. For a while I could restart the engine and it would go away, eventually that stopped working. I learned it was the coolant control valve that was having problems (24001355) and it is on a 5+ month back order. I decided to try repairing it on my own while I waited for parts…It was a 7 hour job to remove, clean, lubricate the valve and its components. It ended up being one of the motor gear boxes that was all gummed up and causing the issue. It was the one with metal clips not screws. I cleaned the old grease on the worm gears and refreshed with new white lithium grease. I did it all in my The garage without a lift on a jack stand.
First, only get into this if your warranty is expired. Take this stuff off: Tire, wheel well, steering linkage, air filter box, two frame brackets (to get air box out) Remove a lower coolant hose to drain most of it…this will be messy. I used a kiddie pool. Don’t unscrew to hose nipples from the valve instead, remove the hoses from the valve, get a hose clip remover tool because they are very difficult to get off. You will have to remove the far right nipple from the valve to get it out. It’s spring loaded with parts you don’t want to lose so be careful. There’s 6 screws holding the valve on, you’ll need a long extension and a little magnet. Make note of the valve rotation position (take a picture) The valve has a rubber gasket in the back against the engine you don’t want to damage. Pull the valve out the top, you’ll need to loosen (not remove) a couple brackets against the engine to do this. One is for the dip stick, the other is holding one of the hose supports. Disassemble and clean the valve. Make note of how everything goes together and its position (pictures would help which I wish I did) Remove the cover that has clips, disassemble the gearbox (again picture first …wish I did that) Clean out the old dried grease. Re lubricate with a plastic safe lithium grease. I used lubriplate general purpose white lithium grease. Put the valve back together and very lightly lube the wear components with the grease. (Might not need to do this) Rotate valve to the original position…reinstall it. Put everything back together (easier said than done) Follow directions in the owners manual for purging the air from the coolant system. I’ll try to share the video I took. It’s not edited for brevity.
The LM2 uses a three way coolant valve that sends coolant to the head, block, and transmission. In the LZ0 GM changed it to a two-way valve. One possible alternative, there is a company known as PPE that sells aftermarket parts for the LM2 and LZ0. They make a replacement transmission coolant valve that provides better flowTim installed one of these on his High Country LZ0 and did a video of it. I don’t know if they make a replacement 3 way coolant valve but you might give them a call. Please keep us posted.
I take it that this is the three way valve that sends coolant to where it’s needed. I think this was replaced by a 2-way valve for the LZ0. Thanks for sharing.