All,

I have a 2001 RX 300, AWD, that has sprung a coolant leak. This is my first post on the forum but have been an avid reader and follower for years.

The leak only happens one the first start of the day. Once the engine is hot the leak stops. I have duplicated the leak by pressure testing the system. The leak comes out from bottom around the front differential/transmission on the driver side. I can not see where the leak comes out from. I can feel all along the firewall side of the engine with my hand but cannot interrupt the flow. I have checked the oil and the transmission fluid, both are not contanminated. Any and all help would be appreciated.

Woods

 

Woods, I hope for your sake I am wrong, but there is a possibility it is the head gasket. With an aluminum block and heads there is a possibility that the leak is stopped when the engine warms up because aluminum expands and contracts so much more than steel does. I would jack the car up or put it on a hoist (but then it will be warmed up and the leak may stop) and put full pressure on the system and get underneath where you can see where it is coming from. (be sure and put jack stands under the car any time you are under it!) When I have been under my DIL's RX I noticed that there is a fair amount of crusty residue at the block to head (headgasket) line. It's only there for one reason, it has been seeping coolant! Probably very, very slowly but there's no other reason for it. They don't have to add coolant very often (about a pint every 4-5 months), but I think it's the nature of the beast that all aluminum engines are going to be more prone to that type of thing. Doesn't necessarily mean you'll ever have coolant leak inside. I hope for your sake that isn't the case! Good Luck and let us know what you find.

 

Thank you. I will be working on it again today. I have access to a lift and will be diving in further.

I will let you know. It is something that has to be fixed because it drips an almost solid stream in the morning.

Woods

 

Well I just had this happen...I cant find my pictures, but to sum it up I had coolent dripping down the back side of the engine on the battery side. Take the top cover of the engine, and then look between the two cylinders heads near the radiator hose, thermostat housing area. Mine was full of red residue... The engine is tilted to the back and I had a leak on the intake manifold gasket, that was slowly running to the back side of the engine and then dripping off of area between the engine and tranny on the bottom. At first I though it was the dreaded head gasket blown, but I took the intake manifold off, and also the thermostat housing. This requires taking the whole intake manifold off. Took me about 8 hours, I had to remove the fuel injection etc. I replaced the thermostat housing seal which is a silicone gasket, and also all of the intake manifold gaskets(which was where the leak was)....here are some pictures of that area: Where I drew a black circle is where I suspect my leak was....Straight above that circle you can see a tiny bit of residue from the leak...it was really bad by the way....Lots of dried residue on the battery end of the engine on top...

 

Thomas1,

Thanks, I believe I have the blown head gasket. When I pulled the spark plugs after pressure testing the coolant system the spark plugs on the front had coolant on them. Then I procedded to check compression on the spark plugs and air cam through the coolant system. Will pull the fuel injection and heads off tommorrow. This is really a bummer but it could have been alot worse. I have been quoted $475 to have both heads reworked.

Woods

 

Good luck my friend, The intake manifold plenum bolt on the rear is a rear bear to get off. it is 14mm and there is not much room. Look under knocks sensor replacement and they tell you how to remove manifold. here is post for that....
http://us.lexusownersclub.com/forums...=knock+sensors