I see drips off the bottom of the transmission bell-housing, but can't find a clear source above it and am looking for ideas.

The vehicle was cold (55degF) and I ran it for a couple minutes to move it into the garage. After a week, the small puddle formed below the rear of the engine, with drops from the bell-housing.

I cleaned it up, and cleaned up what seemed to be dampness on top of the rear intake manifold. Started the engine, and ran it idling for 20 minutes with heater and A/C on. No drops anywhere I could find. There was steam coming up around the EFI plenum a few minutes after starting the engine, but not clear source could be found. Steam went away after the engine was fully warm.

I'm stumped why it might leak when sitting cold for a week, but nothing comes out after running for 20 minutes, pressurizing the system

Ideas?

Video of the steam: https://drive.google.com/file/d/1-W6...ew?usp=sharing



top of rear intake manifold (before cleaning)

Drips off of bell-housing

 

i'd check the pipe just ahead of the fuel filter.. above the oil filter...that's where mine was leaking, at the gasket interface with the underside of the plenum. the leak showed on the back edge of the bellhousing, just like yours.

 

Are you suggesting this pipe? Would the fix then be a replacement of the gasket just above the oil filter?

 

that's the gasket that i replaced, and stopped the leak. maybe check that location in the morning, after it has cooled (since that seems to be when it leaks), to confirm that's where it's coming from before pulling the tube and replacing the gasket.

edit: to clarify, it's an O-ring there, rather than a paper gasket.

 

if you are getting coolant on top of the intake runners, that pipe i showed can't be the source. for that, i'd suspect the temperature gauge sending unit, which is buried down in there, mid-way along the head.

best shot i have of the gauge sender. the male-terminal blade is visible at the base of injector #2 (just above the coolant bypass hose)


another source back there would be the head by-pass plate at the rear...

 

I had to replace that pipe. The flange lip where the o-ring goes was so deteriorated that it was questionable just how great a seal i was getting.

 

@Jimkola were you able to replace your pipe (that bolts under the intake and loops around the back of the engine) with the engine in place?
@wallytoo I'm assuming you did yours with the engine out, given the nice photos.

I confirmed with a pressure tester that 100% the leak is coming from the top of that metal behind-the-head crossing pipe. Letting it sit with about 11PSI on the system for a couple hours and that pipe was soggy wet.

The pipe and the o-ring.

I'm sure there'll be more parts required along the way....just hoping that rear bypass plate bolt that holds this pipe comes out without breaking.

Can someone tell me more about the feasibility of replacing that pipe with the engine in place, and any other tips/tricks?

 

yes, the work was done with the engine removed for a rebuild ('87 4runner #2).

i've replaced the egr bypass on my other (#1) '87 4runner with the engine in place, but it's a bear to remove (and reinstall) the bolts to the back of the head. pretty sure the bypass pipe, running from under the intake/plenum to the other side of the head can be replaced without removing the engine/intake/etc, but it still takes some patience.

 

As wallytoo mentions, the cooler plate is removeable and replaceable while engine is in place...although it is an absolute bear, just getting to all 5 of the bolts reaching in there between the head and the firewall, it is a one hand operation because of the limited space. I used a small 1/4" rachet with a 12mm socket and a ratcheting box wrench to get to mine. Now the pipe, I only disconnected it, I did not snake it in or out of there, but I believe once you pop it out of the intake (removing the 2 small 10mm bolts) and then remove the bolt holding it to the cooler plate and the rubber hose connecting it to the heater valve, it *should* be possible to snake it out there if you need to replace the entire pipe. If you just need to replace the o-ring where it meets the intake, then I think just disconnecting it and tilting it down gives you enough room to do so.

 

I'll share more details once the whole project is done, but yes, I could have gotten away with just the o-ring as it was rock-hard and the pipe was fine. It's a Pandora's Box situation, though, as I've got the throttle body off now to work on the dashpot and replace an oozing hose on that as well. In short, though, all three bolts came loose just fine, and blood loss was minimal.

 

Project is done, and the truck is back on the road.

• Pipe is 87208-35170 and o-ring is 96711-24017. Direct from Toyota was the cheapest parts source. Both original and new pipe are stainless-steel.
• After removal, my pipe looked fine, but the o-ring was pretty hard. I could probably have gotten away with just replacing the o-ring.
• Remove the battery, oil-filter, fuel-filter (2 bolts), and fuel-filter bracket (3 bolts). Optionally disconnect the 2nd heater hose near the one that attaches to the pipe we're changing.
• Rear bolt came off fine with box-end, the two bolts into the intake came off easy with a standard ratchet and long extension. The truck lived its first 10 years in the Salt Belt, so there is some corrosion.
• You'll want a u-joint socket for the fuel filter bolts, and they're tedious to re-install later.
• $40 for a radiator pressure test kit was money well-spent. Both to find this leak, and to ensure all is leak-free before putting everything back together. The kit is leaky at the quick coupler, but it's adequate.
• The coolant hose off the lower engine-side of the throttle body was also leaking -- it's a twisty pre-formed hose. 16264-35012
• Throttle body gasket is 22271-35011. The original one was an hour-long project to scrape off.
• Replaced CSF2306 radiator's crappy plastic drain plug with a brass M10 bolt + copper washer, cut to about 12mm long on a bandsaw.
• Refilling coolant took 16 pints. Filled the radiator, and after three heat-cool cycles the system was purged and happy
• Final pressure test was at 10PSI for four days, and it only dropped down to 9PSI. There was about one pint or so of air space during this test. I only used the cap from the pressure test kit, but outfitted it with a pressure gauge and schrader valve like this.
• 
  Pressure test gauge -- be careful not to overpressure from the schrader valve
  
  Foreground hose can be disconnected for more working room. Background house is to the pipe we're replacing
  

 

Excellent!!! Great follow up with some part numbers for future reference

glad it’s back on the road!!!!