Hi everyone ! Please i need your opinion
i just a bought a Rx350 2009 with 250.000 miles in a dealership. It very beautiful outside and inside but a lot miles and the problem is it started overheating since the day 1 , it gives misfire cylinder 5 all the time . So as an amateur i think i got scammed and fooIed by this dealership . i changed thermostat , coolant sensor , radiator cap , flushed radiator 3 times, still overheats and loses water for few days like 1 liter in 3-4 days and no leaking . I read in this forum about head gasket ,which i didnt know what it was . So now i suspect about head gasket blown or leak .
What do you think i should do ?
-try to use the head gasket sealer repair
-replace complete engine and keep it
-or get rid of this car as soon as possible

lets suppose the head gasket sealer works , does the misfire cylinder start working by its self then, i mean does the coil and spark plug gets dry and start working again or still i do have to change the coils and spar plugs.

Many thanks in advance !

 

Diagnose time. It can take up to 3 or 4 drives to get the coolant properly settled and at a stable level (air removal), so make sure that is not the situation, since after replacing coolant items it needs multiple runs.

1) The actual coolant pump may be shot, but it usually make a racket first.
2) For misfire, pull the plugs and coils on #5 and #6, take a pic, and if they look good, swap these 2, clear the codes and see if misfire stays on 5. Bad luck, #5 is gonna be a bear to get at, search this forum for spark plug DIY change.

Cylinder numbering:

firewall
belt side 1 3 5 tranny
2 4 6

 

The dealer must have known about this ..you should have taken it back and get your $ back before you started fitting new parts.... big job pulling the head/heads if its a gasket problem... if the the coolant is full... you can get a kit that tells you if combustion is in the water jacket, fits on the radiator cap, fluid in a plastic container ..if the color changes its head gasket..... if this is the problem i would try the sealer..

 

Thankyou for your replies!
i wanted to return the car back to those mthf but impossible and also no warranty at all ! Now i am stuck with it and bad luck ! The car runs good for 3 days and then heats up , so i have to add coolant and then its fine for few days . There is no outside leak , so i think the leak might in cylinder 5 as it says misfire cylinder 5 . Thankyou i will try that combustion to see if it changes colour and then i will use the sealer if needed. But then do i have also to change coils amd spark plugs for cylinder 5 as it is misfiring , right !?
thankyou again for your time !

 

If you got no history with the RX pull one of the front spark plugs and look at the tip condition..these plugs should be changed around 125k ...last owner may have changed the plugs....toss up with the coils.....do the coolant test first.....don't worry about the plugs and coils yet ....if the sealer works the plug should be ok, looks like your coolant is going out the exhaust ..engine could have overheated in the past..

 

Already great replies.

Can I please add, you may have 2 different issues going on at once that are not related, always a possibility.

You are loosing coolant and running hot every few days so I'd check the coolant level every time before driving anywhere just to be safe but the timer has started and you are on the clock, leaks get worse over time and loose too much coolant and the engine is junked.

If your car checks out and doesn't have a head gasket leak you can check for moisture on front passenger floor rug for a heater core leak.
Next, with the help of a coolant pressure tester(harbor freight) you can pump up the system with pressure and test for leaks that may not be obvious when engine is not laboring aka sitting idle.

Leaks I've found on my RX330 so far using a pressure tester- one time it was only a loose hose clamp and another time it was a leaking Valley Plate Cover under the intake manifold. If your water pump is on it's way out(as mentioned above), you will know because the pressure tester will let you know as it forces the water thru the weep hole.

PS- I've had loose coil plugs and fuel injector plugs on my back firewall bank come loose, sometimes I have to reach back there and push the connectors on tight- my snaps are broke so they are only friction held. Loose coil plug connector can cause misfires. And- if you have skill and a swivel spark plug extension socket the #5 cylinder plug will come out(on RX330) without pulling the manifold. Do not attempt unless using a spark plug socket with built in extension because if the socket slips off you will be pulling the manifold to retrieve it. lol

 

Good luck reaching down the back and pulling the #5 plug lol.... impossible on the 350...intake manifold has to come off....front cowl/wiper motor etc

 

yup! I can attest to this one first hand!

 

They said it wasn't possible on the RX330 to pull cylinder #1 & #5 but that's not true because I did it.
It's very tight and takes precision and finesse.

We need someone very good to prove it can't be done on the RX350.
It's a bigger motor and may be too tight but I like to see it proven.

Perfect selection of tools and skill will we required if it's possible at all.

 

Thankyou every one for your help and replies . Just to let you know .
i tried the sealer the Bars leak and now i am not loosing coolant
no overheating
no white burning smoke
and check engine lights with Misfire cylinder 5 went out by itself, so no more lights in the dashboard , thankfully i didnt have to change coil and spark plug cylinder 5 .
thankyou again and have a great day !

 

What does it look like under the oil cap? Is it milky or does it look like oil should look?

if you have a head gasket blown and continued to drive it then you are likely looking at warping or even cracking at this point

whag country are you in and how long ago did you buy it? Most used care sales in the us are protected by lemon laws but dealers will always try to screw you over because it’s better for their bottom line.

if there is no coolant leaking anywhere and you’re loosing coolant you likely have an internal leak and the engine is cooking off the coolant. Could be something besides the head gasket like the hose inside the valey under the intake manifold or somewhere else but head gasket could be what’s going on. Is there any thick white exhaust coming from the tail pipe?

again check the oil cap and the radiator cap to see if there is cross contamination and if so you definitely have a bad head gasket and likely even more than that.

I’m not a pro but I know a good amount. Currently struggling with an rx330 engine swap but can’t get the transmission and engine mated back together. Hopefully that changes tomorow.

I think the other person could very well be right that you have 2 different problems happening at once

also good luck with the leak stop. This is most likely going to be a bandage on a severed limb type solution and these problems will return. Might take 10-40k miles but mark my words it isn’t an permanent solution

 

I have used that Bars stop leak before, it works ok with small cracks in the head or head gasket thats beyond the compression gasket ring..drive it and forget about it, that stuff can save you a lot of $$.... you got lucky there...

 

yes you are right it may have been a small crack because i used to lose just a little bit coolant in a week . Hopefully it is going to be good for some time, i know its not a permament solution i am with you . Thanks for your help and time and good luck with your Lexus