Any Truth To These GS300 MK3 Common Problems

Tom163 · July 4, 2017

Hello everyone,

I have searched already but have not yet found anything conclusive from the UK. Over on the US Lexus forums there are many many posts about problems with the 05/06 GS300 MK3 V6 engine but suprisingly little over here in the UK. Can anyone tell me if there were engine differences or was the car exaclty the same?

They are reporting issues with the following:

Carbon build up causing numerous issues like poor idle, excessive oil consumption and more.
Defective piston rings.
ECU needing replacement.

Has anyone experienced these issues or know how common they actually are?

Many thanks

messi · July 4, 2017

I've had 2 mk3 gs300 and no issues at all apart from 1 sticky calipers. Of course i use v power shell fuel which does help to keep the engine clean and running smooth..

Britprius · July 4, 2017

I think the oil burning and ring problem is down to both the quality of fuel in the US, and the fact that they still insist on using ordinary oil rather than synthetic, and often from dubious sources.

John.

Fig · July 4, 2017

Have 12 yr old mk3 2005 GS300, engine fine no oil consumption. Have had sticking rear calipers though.

Britprius · July 4, 2017

Sticking slide pins on the calipers is common across the Toyota/Lexus range.

With regular servicing of the slide pins it is totally avoidable, but the dealers insist they are a non service item. I wonder why. Could it be that it is a very lucrative method of making money from sales of calipers, slide pins, and not forgetting the circa £150 an hour labor charges.

If you look at some of the items on the service sheets you will see things like prop-shaft lubrication. I have not seen a car in years "1960/70 that had lubrication points.

John

Tom163 · July 4, 2017

Hello guys,

Many thanks for all the replies! I am glad to hear the car is not as bad as the light its been painted in via the internet. I was looking forward to finding one till I read some of the things over in the US.

1 hour ago, messi said:

I've had 2 mk3 gs300 and no issues at all apart from 1 sticky calipers. Of course i use v power shell fuel which does help to keep the engine clean and running smooth..

Did you own either for long Messi?

1 hour ago, Fig said:

Have 12 yr old mk3 2005 GS300, engine fine no oil consumption. Have had sticking rear calipers though.

How long have you owned it if you dont mind Fig?

Thanks

Fig · July 5, 2017

I have had it for the last 4years

Oh and the wheels are badly corroded

OldTrout · July 5, 2017

I bought a 98 mk2 GS when it was 7 years old. I had it for 10 years and the only issue I had was ABS pump which I understand was a known issue. My garage sent my pump off to be refurbished and there were no other problems (aside from car park battle scars). I did not know about calliper pins and certainly had no bother with them. I sold the car at about 124k miles and a week later it was retaxed and MOTed and back on the road. I am confident it still is going strong. Burgunbdy flame GS300 R425 ??? - anyone in LOC own it now?

Tom163 · July 6, 2017

Thanks guys,

Does anyone know of a buyers guide at all on here for when I go and view a few of the GS300's? :)

On 05/07/2017 at 9:56 AM, Fig said:

I have had it for the last 4years

Oh and the wheels are badly corroded

Thanks Fig!

welshdragon · July 6, 2017

This may be of help?

GS (2005 - 2012)

Tom163 · July 6, 2017

Thanks for that WelshDragon!

Normski · July 7, 2017

Suggest you check out blowing exhausts too. Every single one I went to see was suffering from this (even main dealer examples).

The largest issue for me though was finding one which had been taken care of. Unfortunately they are getting on a bit now so maintenance invariably starts to suffer.

GSLV6 · July 8, 2017

From my own perspective, I had a 2007 GS300 and these are the issues (all expensive) that mine suffered from:

Exhaust split at the Y junction...a common well documented issue resulting in about a £600 bill for a new rear exhaust section;
premature failure of all shock absorbers...again well documented and due to under-specified shocks, something which Lexus has never addressed;
failure of one of the hydraulic tappet seals meaning engine out and new hydraulic tappets (had the lot replaced) but I gather this was a very rare occurrence;
a re-flash of the ECU needed when the rear soft close of the boot failed to operate
Failure of the wheel lacquer finish, a common issue due to poorly specified lacquer system resulting in a £340 bill to have the wheels powder coated;
bubbling of the paint on the aluminium bonnet requiring a complete respray, all due to a badly done stone chip repair.

That car cost me dear.

oldjoe · July 9, 2017

the main carbon build up problem is on the back of the inlet valves and is due to the use of direct injection so all manufacturers can and do suffer from it. no additive in the fuel will stop it as the fuel no longer comes into contact with the inlet port or valve. there are ways to get rid of it but how successful in the long term we don't know so prevention would seem the way to go. as far as i can see there are two possible ways, one is a catch tray in the feed back to the intake from the crankcase ventilation system. even this may only delay it but using high grade oil and petrol may also help by cutting down on the rubbish coming out of the crankcase. the other is by having an engine like some of Lexus/Toyota ones that use an injection system containing both port and direct injection, unfortunately not used on GS300 according to Wiki. . from what i have seen it seems more manufacturers could go this way but who knows. this is just my interpretation of what i have seen and read online. this is mainly to those who think it is purely a Lexus problem as quite a few do/did on the American forums. IT IS NOT

GSLV6 · July 10, 2017

I thought that the carbon build up was due to the EGR valves fitted on modern vehicles to make EU emissions? The crank-case breather delivers an oil mist, and this often vents to the inlet "downstream" of the EGR valve. The hot exhaust re-circulation gasses contain a lot of carbon sooty particles and it's these I believe that cause the issues. If there's not a lot of oil mist from the breathers, the result is a sooty build up on the inlet valves. It's worse with an oil mist as it forms a sludge. I had the egr blanked off and coded out of the ecu on one of my cars. That cured the issue. Stupid piece of engineering designed to mess up the engine. The sensible thing would have been to engineer them with an expansion chamber and trap with an outlet filter (serviceable) but for economy, they're manufactured to feed straight back into the inlet manifold on most cars.

oldjoe · July 10, 2017

google carbon build up on inlet valves. it builds up to a point where the air flow is affected which brings on management light and if allowed to continue to build could force engine into limp mode. one of the first signs ,if i read correctly , is an uneven tick over. with a DI engine there is no wash off of the valves by fuel as it is fed directly into combustion chamber and not through the inlet port.

GSLV6 · July 11, 2017

Yes, but the build up is still caused by the EGR gas re-circulation system. It's a flawed system.

oldjoe · July 16, 2017

interesting about "bypassing the valve". was that on a Lexus and did you have to reinstate to pass mot?

GSLV6 · January 26, 2021

On 7/16/2017 at 4:36 PM, oldjoe said:

interesting about "bypassing the valve". was that on a Lexus and did you have to reinstate to pass mot?

Sorry for tardy late response...have only just returned here after a long break!

I didn't bypass it on my GS but I did on my VRS Fabia (diesel) and yes, it flew through emissions testing! It also improved throttle response, idle and fuel economy. The EU regulations have made cars less reliable, over complex and shorter lived imho. Every car up until my Lexus cars that I've had, suffered in some form or other with the same EGR issues, some after short miles. Town driving and short trips are worst of all as the engine is in a fuel rich state when cold and this recirculates a lot of carbon deposits. I'm not sure if Lexus would permit the ECU to be reprogrammed to chip out the EGR valve once disconnected though hence I have left well alone on my RX. which we reserve for longer journeys anyway. Our ancient RAV4 is one car we've had zero issues with, nada, not a thing...ever since owned. IMHO, a simple, robust, well put together and over engineered car...one of the most reliable ever made.