LS4Lexus

I have to top off the coolant in my '91 LS400 about every 5000 miles...not much of a hassle really. But I believe I found the source of the small leak (where the yellow arrow points in the attached picture). Would this be an expensive repair?

LS4Lexus

Here's a close-up of what looks to be dried-up coolant. It's a little washed out from the camera flash, but is pink in color.

CUMan

That's the thermostat housing. Looks like you need a new gasket.

It should be very easy to fix. If I were doing this, I would probably replace the thermostat and the gasket.

TLW

honestly

the best thing you can do i s get a pressure tester

you pump up the system to 14 psi

and you will se where it is leaking from

sometimes clamps loosen

hoses split etcetc

good luck

and if you can DIY id say less than $20 in parts from your local car prts store

just need to drain the radiator ,pull off the hose

take off the bolts ,take out the thermostat

clean the area and reverse the procedure

i didnt go into full detail just some of the steps

johnny

LS4Lexus

Thanks for the replies!

A few extra questions...

How do I determine what gasket part # to get?

How often do you replace your thermostat? (miles or time?)

And would a power flush essentially be pressure testing the cooling system?

CUMan

It's been a long time since I replaced a thermostat; however, as I recall, a new gasket usually comes with the thermostat.

I don't think there is any specific replacement recommendation for a thermostat - they are usually very trouble-free. However, with your car being a 91 model, I would suspect that the thermostat that is in there is pretty cruddy. Since you are going to remove the hose and thermostat housing from the engine, I would replace the thermostat while I was in there.

A power flush and a pressure check are two different procedures. I don't think a power flush would tell you anything about whether you have a coolant leak under pressure.

hlovepenn

I just replaced this gasket on my LS400, which is a rubber ring seal. Remove the under pan and drain some coolant off and then remove the obvious nuts and clean and change the seal.
To restore the coolant, you have two choices--the fast one or the slow one. The slow one involves using the reserve tank and refilling it until it's stabilized.
The fast one is to remove the big nut, pointing down, above the part you just worked on. This involves a strong heart, because those nuts are usually tightened with a caterpillar tractor, so it will be difficult to remove! Then start the engine, put a funnel into the opening and add fluid until it is full--it will be sucked into the engine as you add it, and then replace the nut. It is a brilliant design and once you have done it successfully, you wonder why no other company does this in the same way?You have to watch the reserve tank, however, because you can overfill it while doing this procedure. Good luck and take your glycerin for your heart if you need it!

LS4Lexus

You wouldn't happen to have a part # for that rubber ring seal, would you? The Toyota dealer is a lot closer, so I'm hoping to get it from the parts department there.

hlovepenn

I don't have the number, but I just checked RockAuto.com and they have one for about $2.00 vs about $8.00 for the Lexus dealer one. They also have lots of other LS400 parts that are hard to find on the internet. Good luck and let me know if you have any other questions.