2007 GS 350 109,500 miles.
My heater was blowing cold at idle and warm when driving so I took it to dealer. To my surprise, dealer says its a blown head gasket. No other symptoms. No white smoke, no smells, no warning lights on dash, and running fine. Just had VVT gear recall done last week.

Fortunately I have Lexus extended warranty good thru 125k miles and Feb 2014.

I do my own maintenance (plugs, oil changes etc). Have records for all. But have not done coolant change (due at 100k).

Dealer says warranty authorization should be done Monday (today is Friday).

Do I have anything to worry about?

 

When was the last time you checked your coolant level in the reservoir?

 

Not only that, but there should be oil in the radiator reservoir, have you checked for that? Or is it still just sitting in shop?

 

Car is in the shop. I personally have not checked the coolant level. But the dealer did an inspection when the VVT gear recall was done the end of November. That was 600 miles ago.

 

The symptoms you said in post #1 really explains a blown head gasket (to an extreme) in a gist..... I think you have a bubble in the coolant system is all..... I'd have them do a complete coolant flush as another member on here did the same thing and it worked.

https://www.clublexus.com/forums/gs-...new-twist.html

 

That's what I was thinking. BTW, a different dealer replaced the water pump almost 2 years ago. Bubble probably created then. Havent noticed it til now because I have spent the last 2 winters in FL.

 

Yeah, if you are paying for the labor, definitely bleed the system, otherwise if it were me, I'd keep it to myself and enjoy the engine's full gasket replacement and rebuild lol.

 

Dealer says warranty work is authorized. So the repairs wont cost me anything. But i'm still wondering why the head gasket blew (and to be honest, if it really did). Service rep says they noticed a water leak when it was on the lift. That in itself doesn't indicate bad head gasket, so I'm still wondering. I guess if the warranty rep guy authorized the repair, he must be convinced that is the problem. Car has never overheated and always changed oil regularly. Just very strange.

 

From past experiences i doubt it very much that its a blown head gasket.

The symptoms which you described can also be due to a faulty thermostat.

I remember my first 5er doing that and it turned out to be a faulty thermostat at the end, not just that have had experiences with a few friends vehicles as well which was all dew to a faulty thermostat.

But hey if they are going to do the job for free then as the other fellow member said 'sit back and relax' lol

 

Yep. You reminded me of my 89 Accord. As soon as the thermostat opened, the temp gauge dropped and couldn't go back up. The gauge fluctuated bewteen Cold and normal marks.
When the car stopped, the gauge dropped. When the car was moving, the gauge rose a little.
The thermostat was stuck open.

 

Nice.... I'm guessing it's the water pump gasket/water pump leaking. GS350's tend to have that. So many many members here recommend running your car under inspection near the water pump area to prevent further damage.... It just happens, so I can't explain why tbh . Like others, I doubt it needed a head gasket change LOL!

Nice to know faulty thermostat's do that. I've always changed my thermostat when it came time to change the rad fluid. It's what I was told to do a long time ago and I always kept to it heh.

Good to know what the symptoms of faulty thermostats can cause! I love reading up these little tips to diagnose what's wrong with a car.... preventative measure imo .

and AGREED. I wish my car had the chance to go through a full rebuild like some of you lucky members LOL! This 3UZ's really bulletproof.

Nice to know this also! Once again, future preventative diagnosis=a long headache fixed lol.