Please help, Engine Coolant Bypass Pipe (Rear) Part Number: 1635650120 (1 Viewer)

[MulePack]

So, I can't find a thread, video, comment, or even joke about replacing this bad boy or it's gaskets anywhere on the world wide web. Am I an absolute lunatic for even considering attempting this?

I replaced the Tee pipes, that sucked, and I imagine this will be worse. Nervous to start something I can't finish, especially during prime wheeling months in wonderful Colorado. I live for the mountain roads that few can conquer so I'd hate to be out for too long, but I also don't want to be spraying coolant all over the world.

The part and gaskets are like $130 and my shop is quoting me almost $800. not a good sign. Has anyone attempted this? Does anyone have a guide?

Thanks for the help.

 

[JunkCrzr89]

I’ve done it, as have others. It’s straightforward and not difficult, just takes some time because you have to remove the intake plenum from top of engine to access it. Once the intake is off, crawl on top of engine (after stuffing paper towels in the intake ports to prevent crud or tools from falling in), remove the heater hose from bypass pipe, and with a 10mm socket remove the 4 nuts holding the bypass on. Clean up the mating surface and put your new gaskets on, then bypass pipe, torque nuts to spec, and put intake back on and torque those nuts and bolts to spec.

FSM has all of the torque specs you need. @2001LC also has a brief write-up buried somewhere in one of his threads about doing this job.

However, before you dive into this, why do you or the shop think the bypass pipe needs to be replaced to begin with?

 

[medtro]

You can also drop it off at @2001LC 's shop.

 

[JunkCrzr89]

To get a taste of doing this job, see here Coolant leak from bell housing? and Scored 2006LC w/194K GrayBeard

 

[MulePack]

I’ve done it, as have others. It’s straightforward and not difficult, just takes some time because you have to remove the intake plenum from top of engine to access it. Once the intake is off, crawl on top of engine (after stuffing paper towels in the intake ports to prevent crud or tools from falling in), remove the heater hose from bypass pipe, and with a 10mm socket remove the 4 nuts holding the bypass on. Clean up the mating surface and put your new gaskets on, then bypass pipe, torque nuts to spec, and put intake back on and torque those nuts and bolts to spec.

FSM has all of the torque specs you need. @2001LC also has a brief write-up buried somewhere in one of his threads about doing this job.

However, before you dive into this, why do you or the shop think the bypass pipe needs to be replaced to begin with?

Thank you for the info!

Needs to be done because it isn't the hoses, I just replaced EVERY hose in the system and t-pipes and there is still a ton of coolant spraying out of the system with a nice pool of it sitting where the pipe connects to the hose on the driver side.

 

[ShenValley100LC]

Thank you for the info!

Needs to be done because it isn't the hoses, I just replaced EVERY hose in the system and t-pipes and there is still a ton of coolant spraying out of the system with a nice pool of it sitting where the pipe connects to the hose on the driver side.

1. did you ever resolve this?
2. Is this what yours looked like? I cant tell if this is leaking where the hose meets the pipe or at the base of the pipe. I'm thinking base of the pipe because there is no crusty pink on the pipe near the hose only at the bottom.

@2001LC or @JunkCrzr89 If I'm doing this job and I don't know the age or state or the intake plenum gasket is that the time to replace? does the pipe itself need to be replaced or just the gaskets?

 

[JunkCrzr89]

1. did you ever resolve this?
2. Is this what yours looked like? I cant tell if this is leaking where the hose meets the pipe or at the base of the pipe. I'm thinking base of the pipe because there is no crusty pink on the pipe near the hose only at the bottom.
View attachment 2594934
View attachment 2594933

@2001LC or @JunkCrzr89 If I'm doing this job and I don't know the age or state or the intake plenum gasket is that the time to replace? does the pipe itself need to be replaced or just the gaskets?

Looks like the leak is at the base of the pipe where the pipe is press-fit into the bypass/crossover housing. Common for a leak to occur at that join after replacing heater Ts and hoses. Can try cleaning it up and mashing some coolant-specific FIPG (1282B, I think) into the pipe-housing join.

But to answer your question, yes, if you’re going to replace the rear bypass housing gaskets, I recommend replacing intake plenum gaskets, clean out the plenum, and also replace the starter (if it hasn’t been replaced). Technically you can get that bypass off without removing the intake plenum, but it’s a PIA to do so and odds are you’ll drop one of the nuts down under the intake. I think it’s easier to just pull the intake plenum.

 

[ShenValley100LC]

Looks like the leak is at the base of the pipe where the pipe is press-fit into the bypass/crossover housing. Common for a leak to occur at that join after replacing heater Ts and hoses. Can try cleaning it up and mashing some coolant-specific FIPG (1282B, I think) into the pipe-housing join.

But to answer your question, yes, if you’re going to replace the rear bypass housing gaskets, I recommend replacing intake plenum gaskets, clean out the plenum, and also replace the starter (if it hasn’t been replaced). Technically you can get that bypass off without removing the intake plenum, but it’s a PIA to do so and odds are you’ll drop one of the nuts down under the intake. I think it’s easier to just pull the intake plenum.

I have coolant drained anyways because of my mouse in the timing belt problem, so thats a good idea! I love bandaid fixes! And I'm have some of that FIPG lying around.

 

[ShenValley100LC]

Looks like the leak is at the base of the pipe where the pipe is press-fit into the bypass/crossover housing. Common for a leak to occur at that join after replacing heater Ts and hoses. Can try cleaning it up and mashing some coolant-specific FIPG (1282B, I think) into the pipe-housing join.

But to answer your question, yes, if you’re going to replace the rear bypass housing gaskets, I recommend replacing intake plenum gaskets, clean out the plenum, and also replace the starter (if it hasn’t been replaced). Technically you can get that bypass off without removing the intake plenum, but it’s a PIA to do so and odds are you’ll drop one of the nuts down under the intake. I think it’s easier to just pull the intake plenum.

smh, I knocked the pipe in this whole process and now I can actually wiggle it 1/16"-1/8" back and forth and now its leaking more, this truck has not been kind to me this winter. Puking coolant on my driveway just before our first nice 60 degree weekend camping trip, there that goes. I think the FIPG wont stand a chance, so will probably have to replace the pipe/gasket. Sometimes you feel like youre getting away with something driving an old mileage truck and other times...not so much. Now I cant decide whats more of a PIA: taking the intake plenum off or trying to work around it.

I looked up this part # 16356-50120, it looks like its the pipe already fitted into the bypass joint, is that right? Can anyone confirm or direct me to where I can find some part numbers? @2001LC or @suprarx7nut or anyone whos done this job?

If I'm doing this job I assume I should do:
bypass joint with the pipe: 16356-50120
the two rectangular gaskets looks like 16341-50020? are left and right different or just get two? (but should I do the front while im there?)
Plenum gasket 17116-50010?
manifold gasket 17171-50020?
Should I do the Coolant By-pass pipe 16206-50120 and its o-ring?
what else? my starter is less than 100k so I'll leave that. Any nuts or bolts to grab that might break?

I watched @suprarx7nut video on the gasket last night but he was also doing the starter and some other stuff while in there and it looked like a vvti engine. I'm guessing hoping I wont have to do quite that amount of disassembly just to replace the gaskets and the pipe?

 

[suprarx7nut]

smh, I knocked the pipe in this whole process and now I can actually wiggle it 1/16"-1/8" back and forth and now its leaking more, this truck has not been kind to me this winter. Puking coolant on my driveway just before our first nice 60 degree weekend camping trip, there that goes. I think the FIPG wont stand a chance, so will probably have to replace the pipe/gasket. Sometimes you feel like youre getting away with something driving an old mileage truck and other times...not so much. Now I cant decide whats more of a PIA: taking the intake plenum off or trying to work around it.

I looked up this part # 16356-50120, it looks like its the pipe already fitted into the bypass joint, is that right? Can anyone confirm or direct me to where I can find some part numbers? @2001LC or @suprarx7nut or anyone whos done this job?

If I'm doing this job I assume I should do:
bypass joint with the pipe: 16356-50120
the two rectangular gaskets looks like 16341-50020? are left and right different or just get two? (but should I do the front while im there?)
Plenum gasket 17116-50010?
manifold gasket 17171-50020?
Should I do the Coolant By-pass pipe 16206-50120 and its o-ring?
what else? my starter is less than 100k so I'll leave that. Any nuts or bolts to grab that might break?

I watched @suprarx7nut video on the gasket last night but he was also doing the starter and some other stuff while in there and it looked like a vvti engine. I'm guessing hoping I wont have to do quite that amount of disassembly just to replace the gaskets and the pipe?

I have to run into the garage shop for a while, but those bypass gaskets are pretty buried. I did the starter because I had to take all that stuff off to get to the gaskets. The starter was a byproduct of all the work needed to get to the gaskets. Not a small job. Definitely replace any and all o-rings and gaskets in the area. None should be re-used.

 

[JunkCrzr89]

Can anyone confirm or direct me to where I can find some part numbers?

Enter VIN at Partsouq.com

1635650120 is correct for that rear bypass with press-fit pipe. 1634150020 are the gaskets - they are not side-specific. Having done this job on a couple of cruisers, it’s a good idea to buy a couple of the nuts for the bypass, too (9017908153); they can be a bit “squishy” after this many years of engine heat.

 

[ShenValley100LC]

I spoke with a guy at my local Toyota dealer and figured out the part numbers. That nut says it does fit a 1999, so i'll have to see if mine is different. @JunkCrzr89 any time estimate for how long this job takes? I was guessing 2-4 hours for disassembly and cleaning and 2-3 for reassembly?

 

[JunkCrzr89]

I spoke with a guy at my local Toyota dealer and figured out the part numbers. That nut says it does fit a 1999, so i'll have to see if mine is different. @JunkCrzr89 any time estimate for how long this job takes? I was guessing 2-4 hours for disassembly and cleaning and 2-3 for reassembly?

Depends on what else you’re going to do while in there, but 2 hours for disassembly, 1-2 hrs for cleaning, and 1-2 hrs for reassembly is reasonable.

 

[ShenValley100LC]

can someone tell me what setion of the fsm this is in? I cant find torque specs?

 

[JunkCrzr89]

can someone tell me what setion of the fsm this is in? I cant find torque specs?

Engine Mechanical -> Cylinder Head

 

[ShenValley100LC]

Engine Mechanical -> Cylinder Head

Thanks, other than removing the physically picking up the manifold and the stress of trying to not let anything fall in, its really not that bad of a job. All the hoses and vacuum lines are a little confusing but overall 1/2 job.

 

[flintknapper]

Enter VIN at Partsouq.com

1635650120 is correct for that rear bypass with press-fit pipe. 1634150020 are the gaskets - they are not side-specific. Having done this job on a couple of cruisers, it’s a good idea to buy a couple of the nuts for the bypass, too (9017908153); they can be a bit “squishy” after this many years of engine heat.

 

[ShenValley100LC]

View attachment 2614774

I went ahead and put the expensive coolant FIPG around the neck of the pipe at the base of the new one considering it took 520K miles for the first one to leak its probably pointless but I never want to do that again.