Bought the car mid Jan of this year.

Feb 27th: Finished tear down of engine, did a starter replacement. Car was down for a week and 2 days.

March 5th: Wne week after completion of starter replacement, CEL (Knock Sensor Malfunction) comes on and then a few miles later car starts to overheat (never hit red line...). Get home a couple miles later, coolant is pouring from behind the engine bay, seemed to be spilling on top of transmission, as that's where the coolant was pouring from.

Tonight: Just finished tear down number 2 replacing Knock sensors and coolant bypass hose gaskets as thought to be suspect of coolant leak. Started up car after finishing the job, shut off car after 30 seconds, hear spilling. I looked under the car right after and saw coolant just draining fast from the same area of the engine, can't pin point it to anything.

I pressurized the coolant system and it maintained pressure 100%... Let it sit for 30 mins, pressure was still good. I just don't get it.

Going to borrow a snake scope from my buddy and see if I can spot exactly where the leak is coming from... Hopefully.

I don't know. I love the car, it's amazing and I have a lot of work into it but right now I want to just sell the car and get another LS400, especially when I have this waiting to be thrown onto an LS...



I really don't know what to do anymore.

 

Ouch...that hurts looking at what you have into it. At some point, it becomes a lost cause unless you can be sure what you have in is going to be good for long term. So far it isn't that bad. The modification $ was pre-mature until it was 100%. It's fun to get the goodies but on a car with mechanical issues... good thing you didn't put them in.

Edit: Verify the coolant leak and go from there.

That aside, snap a pic of the HID output for me so it can be included into this thread: https://www.clublexus.com/forums/ls4...m-pattern.html

 

it sounds more like your unfamiliarity with the engine is losing you money. at this point you need to call in a qualified mech or shop to finish off the leak woes.

you say you resealed the coolant bypass, but what about the rear EGR Cooler? or a host of other places that could be leaking. if you're set on figuring it out on your own, a bit of UV Dye and a UV light will help a lot.

 

EGR Cooler? I beg of you to please enlighten me on that subject, im going to run a few searches on it now...

EDIT: After looking at this diagram, it says 25680F is the cooler (I thought it was called the water bypass pipe). All the bolts on it are tightened down and those are the gaskets I replaced (25680G according to the diagram)



EDIT #2: Okay i'm confused... 25680F seems to be the water bypass (1635550030 @ $100) and then when I search cooler I get this diagram with a different part number (2560850010) and now shows $1060............ What gives?

 

did you check the FSM and see if those gaskets require FIPG or sealer...?

 

I don't have a FSM sadly, but I didn't see any sealer on the gaskets that I removed, so I just popped the new ones on, I noticed that the rubber mates to the surface and crushes though, so I figured it was good?

Please check my previous post as I just finished editing it a bunch... I'm confused on the differences?

 

dear confused, 1635550030 is on the front of your engine.. 2560850010 is the egr cooler on the back of your engine. I have replaced starters on two LS's and have had no leaks. just take your time, and do it right, or get professional help.

also, when we replaced the motor mounts, while lifting the motor up, we cracked the heater control valve on the firewall, that will also be a leak area that would be on the tranny.... you might want to look..

 

now u know why i recommend knock sensors and connectors be replaced when the starter is done...if nothing else i hope others learn from this. sorry about the trouble u r having,live and learn

 

there is a FSM on ebay right now for the 1997 ls400.

http://www.ebay.com/itm/1997-Lexus-L...r#ht_610wt_756

 

Yeah, that's not leaking billy, I wish it was so i'd have a running car right now. I pressurized the system and can't find a single leak whatsoever. Even if I did replace the knock sensors the first time around, i'd still have my coolant leak everywhere. I can't find the leak whatsoever. I have no reputable shops for Lexus' in my area (92545) and the nearest Lexus dealership is an hour away. The Toyota dealership in my town is scandalous, they'll charge you $100 diagnostic fee for a missing steering wheel if you said you were missing a steering wheel. They also raise the prices of their Lexus parts there costing more than a Lexus dealership.

 

Damn I'm getting a headache just reading ur thread. I feel you man, i was having problems after problems. That's why I got rid my ls. Good luck,do what's right for you!

 

did my first line "un-confuse" you... dear confused, 1635550030 is on the front of your engine.. 2560850010 is the egr cooler on the back of your engine.

 

Yeah it did, thanks.

Now i'm just wondering what the heck is leaking.

 

Don't know how much of an engine teardown you did, but if you replaced the timing belt and removed the thermostat housing assembly on the front of the engine (the assy. that has a round mating section at the top, and a rectangular section at the bottom), it could be leaking on top of the valley and going all the way to the back of the engine before it finds a way to the ground. That happened to me when the sections weren't quite mated properly, and the FIPG blew out after the engine heated up. Could not see the leak until I took several engine covers off (again!). Don't know why it wouldn't show up under a pressure test, though.

Steve

 

Teardown is probably a bit vast for my situation, but taking off the manifolds does involve quite a bit of work. I pulled that off last teardown, but not this one. Kept it on the upper intake manifold.

I'm still at a loss on how it wouldn't show up on a pressure test, yet it leaks right off the bat the second the car is started.