I have a 1992 Lexus LS400 thats got around 160k miles on it. It was sat around for a while because the previous owner had issue with it drinking the P/S fluid through the intake. I fixed this the day I got it (Bypased) and it went and passed our emmissions program (AirCare) the day after with decent numbers.
Unfortunately there is a rather loud and annoying sound produced within the engine. It sounds VERY MUCH like a Diesel engine with a RPM specific Rat-Tat-Tat noise. Its gets consistantly faster with RPM, but when reved hard it sort of "buzzes" on the way back down. Its not present on a very COLD start (IE first of the day or several hours 6+ inbetween starts). Seems that its FULLY loud once the startup RPM's drop to there warm idle state.
It sounds as if its coming from the base of the Intake Manifold on passenger side.
I've had a glood listen around using the extention bar to the ear method and it seems impossible to pinpoint. The loudest thing found using that method is the 2 fuel rails. I'm even wondering if it could be a fuel injector itself?
Although it didn't sound as if it was coming from under the valve covers I went ahead and checked clearance anyway and all were within specs.
I'm a little bit lost as to where I can go next...
I hear the EGR cause a noise on these occasionaly but I would imagin that to be a typical exhaust blowing noise rather than a rattle or tap?
Something IN the manifold?
Fuel Injector?
I should say that it drives fine, seems to make good power and MPG is around what I would expect.
Any help greatly appreciated!
Dan
Unfortunately there is a rather loud and annoying sound produced within the engine. It sounds VERY MUCH like a Diesel engine with a RPM specific Rat-Tat-Tat noise. Its gets consistantly faster with RPM, but when reved hard it sort of "buzzes" on the way back down. Its not present on a very COLD start (IE first of the day or several hours 6+ inbetween starts). Seems that its FULLY loud once the startup RPM's drop to there warm idle state.
It sounds as if its coming from the base of the Intake Manifold on passenger side.
I've had a glood listen around using the extention bar to the ear method and it seems impossible to pinpoint. The loudest thing found using that method is the 2 fuel rails. I'm even wondering if it could be a fuel injector itself?
Although it didn't sound as if it was coming from under the valve covers I went ahead and checked clearance anyway and all were within specs.
I'm a little bit lost as to where I can go next...
I hear the EGR cause a noise on these occasionaly but I would imagin that to be a typical exhaust blowing noise rather than a rattle or tap?
Something IN the manifold?
Fuel Injector?
I should say that it drives fine, seems to make good power and MPG is around what I would expect.
Any help greatly appreciated!
Dan
Last edited: