Coolant Leak - Bypass pipe O-ring

Update:

For anyone that may have a coolant leak on the front crossover gaskets (04 Tundra). You can get to those gaskets without removing the entire air intake manifold. I removed the throttle body and the fuel pipe which gained access the the coolant crossover bar. You will need to form a new gasket for the coolant pipe and replace the o ring (above). You will also need a new gasket for the throttle body part number 2227150042. I drained the coolant from the radiator and it would have been a cleaner job if I had drained the block as well.

 

Thanks for the update sunmountain505, very helpful. I do have a question. What do you mean when you say you’ll have to “form a new gasket for the coolant pipe”. Is that not something you can purchase?

 

@Solfitaustin You have to use some gasket making material on the coolant pipe to make the seal (FPIG AISIN AB1027B1 you can find it on Amazon). It has been a while since I did this so I didn't remember exactly which part of the pipe gets the goop. But yes all the other gaskets for the job you can buy.

 

SunMountain5 do you know if the same applys to my 2006 4.7 DC?

Does apply to a 2006 DC as well?

 

It will apply as long as you got a 2uz

 

Anyone know if there's more than 2 bolts holding the bypass pipe housing on behind the t-stat housing? I'm trying to get to the o-ring, thanks in advance.

 

There shouldnt be, but there should be gasket maker/FIPG as well, so its likely "glued in" by that. Speaking from experience with my 1UZ.

 

Two bolts, one long one and one short one. Just did this today. Thought it was my water pump so did pump and timing belt, but ended up being just the o-ring on the bypass pipe (through the valley). What was odd is that it wasn't leaking out the back of the valley (near transmission) like most people report. It was leaking down the side of the block behind the alternator. As such I thought it was the pump seal... but it was just the bypass o-ring. :-(

Oh well, at least the timing belt replacement is back on schedule (200k, last replaced at 140k, so a little early).

 

I think that's what's going on with mine. Was able to trace the leak to the backside of the thermostat housing. Coolant on the backside of alternator as well.

 

FYI, inside the community megathread, the general info thread with everything you need to know about your truck (including TSBs, leaks, nuisances, known issues etc.) we have this info, and it probably covers your leaks:

• Coolant leaks: Three common causes: One is the is the gasket behind the thermostat housing, another is the coolant crossover at the rear of the block, and last but not least, old radiators is another source. Here's a list of things to check if you're losing coolant. For repairing the leak behind the t-stat housing, check this out. For the coolant crossover tube issue, you'll likely find coolant at back of the block, near where the trans and engine meet, check this reply for video/fix. This post is for leaks at t-stat housing/inlet neck. This reply contains links to three other off-brand/odbball leak cases. For radiator leaks, this is one example of a tiny one - always replace with Denso brand radiator, and know different cab types use different sizes, careful where you order, scAmazon especially tends to deliver damaged products often (RockAuto has a spotless record with forum members). Proactive radiator replacement is wise. The transmission line routes through the bottom of the radiator ... go look up "pink milkshake", it happens in these trucks.

There's a parts-finder sticky thread that can show you exploded diagrams and give you part numbers posted near the top of the thread list, too. In case you need to see how everything goes together.

You can also download a copy of the service manual. See the Service Manuals link in the megathread, right around line 6 of the 1st post.

And yes ... I realize one of those links above links right back to this post. Sometimes with linkouts we get some duplicity. Better to over-connect than to underconnect, y'know?

 

Thanks, @shifty` !