Coolant Leak @ Back of Engine...Pull Trans or Engine?
02-17-12, 04:30 PM
#1
Coolant Leak @ Back of Engine...Pull Trans or Engine?
Hey All. My son's 92 SC400 w/ 1UZ just sprung a coolant leak somewhere on back of engine. It drains at bottom 2 bolt flywheel cover where auto trans meets engine. Best I can tell it's not the heater hoses or the throttle body coolant hose. Based on where the leak drains too, I'm suspect it's the water bridge gaskets on the passenger side. Very tight quarters back there, as many of you likely know. Seems to leak only when engine running...so far. Attached is pic I swiped from stevechumo reply to another posting, that shows rear of engine. I modified it to show how heater hose bypass & my prior fix on leaking throttle body hose. Unfortunately my engine is not removed like his was.
So...assuming I may need to get better access to the rear end of the engine to find/fix the leak, which is the better way to go; pull the engine or drop the trans. I'm not looking forward to either. Any other ideas on diagnosing how to pin-point the leak?
So...assuming I may need to get better access to the rear end of the engine to find/fix the leak, which is the better way to go; pull the engine or drop the trans. I'm not looking forward to either. Any other ideas on diagnosing how to pin-point the leak?
02-17-12, 05:27 PM
#2
1JZ Single SC400
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I had a similar problem.. might be the oring on the back side of the water pump. It will show leaking where the tranny and motor meet.. see if you can figure that out.. the oring might have got pinched or gave out.. good luck.. sorry i couldnt be more of help..
02-25-12, 12:53 PM
#4
Nope wrong again. It is coolant afterall.
Working on pulling the trans today. Had a tough time loosening the trans oil cooler lines. My 17mm flare nut wrench is a cheapo brand & it was flexing open & started to roll edges on the nut. Had to resort to using a vise grip to hold the flarenut wrench closed.
02-26-12, 07:11 AM
#6
I'll know soon enough. Did water pump, TB, among lots of other stuff ~ 3 years ago, so I don't supect waterpump. Auto trans unbolted & on it's way out. All stuff off according to http://www.lexls.com/tutorials/trans...n/removal.html.
All the way thru step 16 except the last 3 words " and it's off". Trans lowered a bit & pulled back to point where flange hits the body. The lower trans oil snorkel is welded to the trans oil pan and limits how much I can tilt trans relative to engine without risk of bending/breaking the tube. Still appears that the shaft is not clear of the torque converter. Trying to remember how I got trans off a couple years ago when I replaced rear seal, & can't recall if I had to unbolt torque converter from flywheel 1st. just to drop trans.
Anyone go thru this recently or has better memory than me to know how to get past this last step of removing the auto trans.
PS: 1992 SC400 1UZ Auto trans (almost removed)
All the way thru step 16 except the last 3 words " and it's off". Trans lowered a bit & pulled back to point where flange hits the body. The lower trans oil snorkel is welded to the trans oil pan and limits how much I can tilt trans relative to engine without risk of bending/breaking the tube. Still appears that the shaft is not clear of the torque converter. Trying to remember how I got trans off a couple years ago when I replaced rear seal, & can't recall if I had to unbolt torque converter from flywheel 1st. just to drop trans.
Anyone go thru this recently or has better memory than me to know how to get past this last step of removing the auto trans.
PS: 1992 SC400 1UZ Auto trans (almost removed)
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02-26-12, 11:47 AM
#8
Yeah that did the trick. Needed just a bit more lean to the rear. No obvious leakers back there though. From above, I can peak into the valley below intake manifold. Guess what I see...coolant. Added a bit more water to the puddle & it leaks down back of engine. Now to check for leakers up top. On the positive side, at least I'm not laying on my back for a while...until I have to install the trans again.
02-26-12, 06:37 PM
#9
Rear Coolant leak Path
So here's how the coolant made it's way to drip at the bottom rear of the engine/tranny interface. Appears to be leaking at the water inlet housing O-ring or less likely from water pump rear o-ring. Coolant leaked into valley below the intake manifold & migrated aft to 2 drain holes beneath the starter. From there it trickles down around the cover for the rear main seal & comes out at 2 bolt cover plate at front of tranny. Kinda bummed that I pulled tranny to figure this out, but oh well.
Good advise from 1992Lexus & spoolxexo. Looks like I learned the hard way.
So for anyone else encountering coolant drips at bottom rear where engine/tranny meet:
Step 1: Look at valley beneath intake manifold. A bit difficult to get good view. Try from front, by thermostat & also from passenger side. If you have coolant puddled in this valley, see step 2.
Step 2: Don't pull your tranny!
Several possible coolant leak sources on top, as you can see from 1st slide.
Good advise from 1992Lexus & spoolxexo. Looks like I learned the hard way.
So for anyone else encountering coolant drips at bottom rear where engine/tranny meet:
Step 1: Look at valley beneath intake manifold. A bit difficult to get good view. Try from front, by thermostat & also from passenger side. If you have coolant puddled in this valley, see step 2.
Step 2: Don't pull your tranny!
Several possible coolant leak sources on top, as you can see from 1st slide.
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02-26-12, 06:44 PM
#10
1JZ Single SC400
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I am glad you figured it out, even though it was the hard way. I was able to finally help someone with almost 4K post.lol I felt like it was that .59 oring behind the water pump from the start. I just didnt want to be the bearer of bad news of what you have to do to fix it.
02-26-12, 07:08 PM
#11
I've seen lots of your postings & I know you offered good advise...at least one other time Ha-Ha.
I think I'll try the easy way this time, after I get tranny back on. Will change the water inlet O-ring 1st. If fixed then great. If not, then may need to go deeper to water pump.
I think I'll try the easy way this time, after I get tranny back on. Will change the water inlet O-ring 1st. If fixed then great. If not, then may need to go deeper to water pump.
06-10-12, 08:27 AM
#12
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coolant leaks
I've seen lots of your postings & I know you offered good advise...at least one other time Ha-Ha.
I think I'll try the easy way this time, after I get tranny back on. Will change the water inlet O-ring 1st. If fixed then great. If not, then may need to go deeper to water pump.
I think I'll try the easy way this time, after I get tranny back on. Will change the water inlet O-ring 1st. If fixed then great. If not, then may need to go deeper to water pump.
06-18-12, 06:44 PM
#13
Replacing the Oring at aft end of inlet housing did the trick for me. That was a piece of cake after messing with the trans.
Be sure to check the valley on top of the block to look for coolant puddled there. Mine had it, I just didn't check up top first, & jumped to the (wrong) conclusion that it was between engine & trans, where I saw the drip. It's kindof like the leak I had in my roof. Where you see it dripping is not necessarily where it's leaking.
Be sure to check the valley on top of the block to look for coolant puddled there. Mine had it, I just didn't check up top first, & jumped to the (wrong) conclusion that it was between engine & trans, where I saw the drip. It's kindof like the leak I had in my roof. Where you see it dripping is not necessarily where it's leaking.
