WP in YQR

Hello Lexus RX 300 Forum "Experts"

1999 Lexus RX300 Front Exhaust Manifold has a slight crack and I want to replace on my own. (Causing a bit louder engine noise)

1) Any advice on acquiring replacement parts? (Dealership has manifold for around $300 CDN and two sets of required gaskets for about $50 CDN. Dealer asking around $600 for parts and labour to repair)

2) Upper three bolts on manifold look rather straight forward to access, but lower three may be a bit more work.....any advice here?

3) One concern I have is that the studs may break off. I'll be using an air wrench. Comments or advice?

Thanks for considering my situation and I look forward to your comments!

WP in YQR

TunedRX300

Where is the crack? You might find an exhaust shop to weld the crack and hopefully no need to replace the whole manifold header. How did it crack?

LB Lex

I agree, the crack can be welded. You'll save money and it will be just as good as buying a new one.

As a general tip on changing exhaust headers, spray all the bolts and the oxygen sensor with LiquidWrench, WD40, or other penetrating grease and let it soak for a half hour or more to loosen up the bolts because you don't want them to snap off or strip. Also, you'll probably need to loosen the bolts to the exhaust, so you'll need new gaskets for those too along with a new exhaust manifold gasket (unless the old one is still in good shape). I know that the exhaust gaskets that Lexus has between the exhaust piping sometimes come apart when you remove them, that's another reason you might want some extra ones on hand.

On another point, I had a GS300 and there was an exhaust leak near the engine. Two muffler shops thought it was a cracked exhaust manifold, but I took it to a third shop and they found the leak between the exhaust manifold and exhaust piping. The first two shops I took it to were a little lazy and didn't do a thorough job, but the guy at the third shop spent some time trying to find exactly where it was because he didn't want me to waste money and didn't want to end up doing the job twice. It was also difficult to find because there is heat shielding on the exhaust manifold that makes diagnosis difficult. So, make sure the crack is on the exhaust manifold before you proceed. Those things are hard to crack, so most likely it might be something else that's leaking.

WP in YQR

Dear LB Lex & TunedRX300 - Cracked Exhaust Manifold:

Thank-you for your efforts to provide a response. Much appreciated!!!

I have attached a picture of the crack in the exhaust manifold of my 1999 RX300. Hopefully you can see the hairline crack is barely noticeable and in a very awkward position. The slightly louder engine noise while idling is barely noticeable but I didn't want to get into a situation where-by I was forced to repair it while on a trip and I didn't want to wait for it to get any worse.

I appreciate the advice and suggestions to weld and once I get the manifold off, I will pursue this option. My belief is that the slight crack (no idea how it cracked...no dents or occurrences of bumping the exhaust pipes) is too close to the threads of the oxygen sensor. I think that welding in this area will result in damaging the threads in the manifold and prevent re-installation of oxygen sensor. SEE ATTACHMENT. Comments?

I haven't gotten a quote for welding, but I am estimating it to cost around $80 to weld. I was thinking that this vehicle has been totally trouble free so I thought spending $350 was reasonable repair.

Again, appreciate the efforts to comment and provide advice!!!

Best always,

Wayne

Regina, Saskatchewan, Canada
wfks@accesscomm.ca

LB Lex

Once you take it off bring it to a welder and see if they could do it. If it can't be welded why don't you call junk yards and see if they have any used ones, they would be a lot cheaper than the dealer. And of course the last resort is to buy it new from the dealer and install it yourself.

Make sure you soak all the bolts with penetrating lubricant for at least an hour so the bolts would be easier to remove. It should be pretty straight forward from there. There might be some specific steps or things you have to remove, I'm pretty sure some RX owners who have some experience doing this can give you a little more detailed advice.

TunedRX300

Heat cold cycles probably caused the crack - ask a good exhaust shop for professional opinion.
You should just buy the front manifold gasket. Re-tighten the manifold after a week of "settling". Good Luck.

gcrim21

Have you checked prices at a Toyota Dealer? Or possibly if you know a good independent garage that can do the work?

MarkG2000

I have almost the exact situation.
Me...I failed smog....needed to change the Air Fuel Ratio sensors...2 of them. Had it done at the Ca State Smog shop....$426.
Now I'm good for 2 years. The numbers vastly improved...however I also have a crack in the manifold. I don't have the tools to do the job.
I agree on the welding....might damage the threads once it's off. I'll consult with welder...but anyhow....is there a part number for the manifold and gaskets?

Thx guys

JAB

Several years ago I noticed exhaust noise, but only when cold. Turned out to be a crack in one of the exhaust manifolds. Was told it was a common problem. Had both manifolds replaced when my transmission failed; paid parts only, no labor.

MarkG2000

Can u remember the part number...and gasket. How can you not pay labor? Unless you DIY! Was it difficult to change and how long did it take?

thx

thomas1

gASKET IS 17320010 manifold 1710520010

JAB

Apparently I was unclear. When my transmission failed (out of town, no Lexus dealer in the vicinity) I had the RX towed to the local Toyota dealer. I was already paying a lot for a reman tranny and the labor to install it; its probably not a big job to replace the exhaust manifolds if the car is already on a lift and the tranny has been removed.

bufferdan

Looks like that can be welded on the car. Check around some places. Shouldnt cost much at all!

MarkG2000

Will check welders....but gasket will need changing
nonetheless.
Tranny doesn't have to be removed. Mine is the 2000 and the problem is
in the front of the engine or more towards top front.