Mystery coolant leak found.

for the past few months I have parked her because of a slow coolant leak and no time to tear into her. I pressure tested the cooling system both hot and cold and absolutely no leaks under pressure. Take the pressure tester off and come back in 5 minutes and new drips of coolant on the bottom of the trans bell housing. Not a leak, drips. I was hoping and praying it was the bypass tube under the intake but it wasn't that. When I was taking the intake manifold off one of the rear drivers side bolts was finger tight. I was hoping it was that but there were no signs of a coolant trail... damn, got to pull the motor.

She is a 1996 extra cab 3.4 4X4 with 180k on the chassis and unknown on the motor... it was the daughter of a friends truck, she drove to an early grave because she never checked the oil. Don't know if it is a JDM or USA wrecking yard engine.

There was really on one major issue taking this motor out... there is next to zero room to take the torque convertor bolts off the flex plate. I looked through the starter hole, nope, no access. I looked underneath the inspection plate, nope nothing really. I looked on the D/S of the block/trans, nope, nothing there. I ended up lifting the motor off the mounts some 4 or 5 inches and if you look really close you will see where there is a recess in the oil pan that is maybe 2 inches wide and you can just barley slide a long extension and flex socket and get to the bolts. That is going to be fun to reinstall them.

I found 2 other things I wasn't really expecting, the first is the rear main oil seal leaks the second is that the previous installer never greased the nipple of the torque convertor where it rides on the end of the crank. A little grease put here and it will eliminate a very hard to find chirp.

I guess I will replace all of the oil seals while she is out and reseal the valve covers/cam end seals.

Going to pull the steering rack and take a look see... slight loss of PS fluid.

 

So we're is this leak?

 

I would imagine it’s coming from from the crusty freeze plug.

 

Nothing ever goes as planned. I figured the engine is out and there is lots of room in the engine bay, lets replace the leaking steering rack. It took 10 minutes. I got to looking over the engine and started to notice some things, leaking rear main, what looks like a leak from the oil pan and the water pump looked pretty old. Might as well reseal the engine and do a complete water pump / belt / tensioner kit while it is on the stand. I did run into a few surprises. The use of RTV... I am not a fan. There was a collection of hard carbon around the drain hole and few bits on the pickup screen. No amount of oil changes was going to get that carbon out of the pan as the drain hole/plug is not the lowest surface in the pan. The only thing that has me concerned is the groove in the rear main sealing surface. I installed the new seal at a slightly different depth hoping that the new seal will ride on a good new area of the crankshaft.

 

I'm really impressed that you can just decide to one day pull the engine to look for a leak. Looks like a tremendous amount of work!

 

180k on the engine. If they weren't replaced before they will show signs now

 

I had eliminated all other possible sources of a coolant leak so it was either the core plug or something bizarre.

The story continues... during the engine removal process I was un-clipping electrical connectors and I came across a connector on the drivers side of the auto transmission that was missing. The wires were pushed onto the pins of the connector that was installed in the transmission. I made a note of their positions and finished pulling the motor. I went to my local Toyota dealership to get a replacement connector and it is NLA, no longer available, damn, now what. I did some searches on the forum here but all of the people who have 1 gens for parting out either had junked the truck long ago or the harness was gone. I found a 99 Tacoma 3.4 auto trans in a wrecking yard with a good harness but he was asking $125. I didnt have a choice but to buy that harness for one connector. BTW the connector is for the shift solenoids. The new connector fits my trans so I start the process of stripping the new old harness and my old bad harness. I checked the wiring manual and the color code of the wires is no where close to what it should be and I found that odd. I strip more of my old bad harness and I see why... eek.

In an effort to sooth my pocket book about a $125 connector I look at the new old harness and discover that all the plastic housings that hold the wires on the intake are in fantastic shape, well that was unexpected. I inspect my old harness for other potential issues and discover why intermittently the AC fuse would blow.

I spent the next few hours cleaning the harness of road grime, stripping, soldering and covering the new splices into my old harness. I have other wiring mods I am doing while the engine is out. Cleaning up the wiring for the additional horns, the bumper mounted driving lights, the off road lights, the winch relay and wiring in some 55w / 100w H4 bulbs.

The bottom picture is the unobtainium $125 plug... ouch.

 

Wow G-man... this is getting interestinger and interestinger. Must be satisfying to fix a chewing gum repair like that and make it into something that will last.

 

this truck is supposed to be my main use pickup in Cabo. I was supposed to drive her down there 6 months ago but stuff at the business got in the way. Kind of glad now that I was delayed, much easier working on her up here than down there.

 

Wow, what a hack job someone did to that poor thing!
.

 

replace the whole harness if you can, screw it.

 

What would cause this??

 

question is, why couldn't you start a new thread?

Water dripping onto that area and no exposure to sunlight.

 

That looks like a weeping freeze plug to me.

 

Looks like the new engine wasn't cared for much better than the old coolant and oil change wise. Dirty oil cuts grooves like that.