ychen

Thanks. I am positive it's coolant and on both sides. I just need to determine where the coolant comes from.

ychen

All the timing covers are off now. It seems the coolant is coming along the ridgeline of the water pump on both sides. Any chance that the coolant leaks come from source other than the water pump (including gasket)?

My current plan is replace timing belt (it has cracks) & WP and all other moving parts. I ordered AISIN TKT-030 from amazon. I was examining the timing belt and found one of the nylon thread was cut on one end of the timing belt (pls see the picture). Is this going to compromise the function and longevity g the timing belt. Should I exchange with amazon? Thanks again for your help.

ychen

I failed to mention that the coolant has been leaking since I bought it (12/31/2013) even though the car has not been started since early January. Thanks.

dashan

You may also want to replace the fan bracket while you are there.

ychen

Finally I finished removing everything in the front of the engine. it seems the coolant leak was from the water pump. However, I think I have much more serious issue now. The engine cylinder headers at the front (the two red arrows) have been corroded due to the coolant leak and the headers are leaking (Please see the pictures) oil I presume. What are my options now? Do I need new cylinder headers? Thanks in advance.

LScowboyLS

I cannot see your photos very well on this phone (not at home) - but those look like freeze out plugs

why are you calling them headers?

headers are a tuned exhaust manifold of equal length pipes for each cylinder, and your LS400 doesn't have them from the factory

ychen

Sorry for my ignorance. Can I just replace them?

LScowboyLS

can't see well enough to tell you what the arrows point to for sure, but if they are indeed freeze plugs, yes you can replace them and they are not expensive, but they will have to come from the dealership to insure proper fit (online dealership like Sewell Lexus, Lexus of South Atlanta parts, Park Place Lexus, or Lexus Parts Now are all fine)

ychen

Thanks to Cowboy for your prompt response. The two arrows point to the corroded parts inside the two discs. I could not find any thread on how to replace them. Is it a hard task? Thanks again.

LScowboyLS

it is easy to replace the freeze plugs - Toyota calls them "PLUG, TIGHT, NO.1" - the part number is 96411-43000 - the cost is $3.83 each at Sewell Lexus

I would replace at least both of the freeze plugs on the front side of the each head, and I would take a mirror and a strong light and take a good look at the identical 2 plugs on the back side of each head, and replace those as well if they are leaking or corroded, all 8 freeze plugs in the heads are the same part number.

the cause of this is usually due to people not changing their coolant using Toyota long life red and distilled water every 3 or 4 years!

the ones on the back of the head may be too hard to get to, with the heads in the car, I am afraid, so hopefully those will look OK, or else this has become a big job!

LScowboyLS

here is a video how-to

ychen

Thanks again Cowboy!.

LScowboyLS

to get the tool he used (a little bit expensive) - you can see if any auto parts stores will loan it to you, otherwise, I can help you find it on ebay, then you use it, then put it back on ebay, sell it, and get your money back!

LScowboyLS

here are some of those Mac Tools freeze (expansion) plug installation tools on ebay for around $50-$75

ychen

Thanks for the link on ebay. I have watched some videos on Youtube. It seems pretty straight forward. I will replace the 4 on the front for sure. The ones on the back are really hard to see let alone replacing them.