As some of you may know, my engine has been consuming oil in the range of 1L every 1000 km to 1 L every 1500 km. Under warranty, Lexus Canada ordered dry wet compression tests on the RCF engine. They claim the results look ok. Long story short, they have now denied my warranty claim on the powertrain, due to the fact that I have installed and aftermarket exhaust???

I know I've posted the results in a separate thread but I think that it got buried. I would greatly appreciate some more feedback from the experts on the compression test results. Please see posted results:

From the research that I've done, the dry results seem on the low side. I don't have the specs for this engine and Lexus will not release the specs to me. However, I have found that the difference between wet and dry should be 10-15 psi normally. Here you can see that the difference is about 40-50 psi. As some have mentioned this reflects a problem with the cylinder wall / piston rings. I find it hard to believe that the rings have worn in around 4-6K km, which is when I discovered my engine oil consumption issue. So I'm thinking:

-glazed cylinder walls
-cylinder bore out of round
-damaged / cracked piston rings, piston ring lands
-improperly installed piston rings
-pcv system not working properly

all which could potentially lead to engine oil consumption. Thanks for any further feedback.

Oh if someone could provide the specs for this engine it would be greatly appreciated. Thanks.

Wolfman

 

I'm not a mechanic, but I believe normal compression should be around 165 PSI. 140s seems low -- though the consistency between cylinders is obviously good. No way that much oil consumption is normal though. If Lexus is telling you it is normal and your car has no problem, I would take off that exhaust and trade it in to that dealer for a 2018. Then it becomes their problem instead of yours.

BTW, there is no chance that an exhaust would cause your motor to burn more oil.

Good luck.

 

Direct quote from the factory service manual. Their own manual says this engine is bad. Three cylinders are below the minimum spec, so unless you are at 5000 feet altitude, this engine needs a rebuild.

(m) Depress and hold the brake pedal, and turn the engine switch on (IG). Then check the compression pressure.

Standard Compression Pressure:

1400 kPa (14.3 kgf/cm2, 203 psi)

Minimum Compression Pressure:

1000 kPa (10.2 kgf/cm2, 145 psi)

Pressure Difference between Each Cylinder:

100 kPa (1.0 kgf/cm2, 15 psi) or less(1) If the cylinder compression pressure is low, pour a small amount of engine oil into the cylinder through the spark plug hole, then inspect it again.

 

Lobux, thank you so much for providing this info that Lexus was unwilling to provide. I now understand why. My engine is a complete disaster with the readings that were obtained.
I can't believe the Standard Compression Pressure spec is 203 psi. My engine cylinders are in the 140 psi range!!! 4 cylinders don't even meet the Minimum Compression Pressure of 145 psi!!!

This statement in their manual says it all:

If adding oil increases the compression pressure, the piston rings and/or cylinder bore may be worn or damaged.

This is simply outrageous and callous behaviour by Lexus Canada.

Wolfman

 

Is the oil consumption issue effecting all RCF model years?

Has it done it on the IsF as well ?

 

Neither my IS F nor my GS F have any oil consumption problems. Not sure what you are talking about. This is a problem for certain individual vehicles only.

 

^
I see
much appreciated

seeing wolfmans thread I thought maybe all RCF was having oil issues

have you had the fuel pump and the brake pad done on yours? I looked at a few CPO and most seem like new pads and fuel pump tsb for buzzing noise done

 

Unbelievable that a Lexus dealership DENIED the engine is defective and just do the honorable thing!!! I wonder if Lexus HQ even knows about this claim?

Which makes me wonder sometimes? I mean if that dealership honored the claim, they still get paid for the service, right? Or doing warranty/claim work is "just not worth the time/effort by the Lexus dealership"?

Now knowing the official Lexus engine specs, I would definitely insist on "a brand new replacement" to make it "whole again". Forget about repairs since they don't want to anyways.

 

Any updates on this, i.e. did Lexus ever make it right?

Also, while changing my plugs soon, I'm going to do a compression test and am curious Lance if those service manual figures depend on the engine being cold or hot (several generic sites discussing compression tests insist on testing a warm engine), as well as if the throttle should be floored so the intake plenum is kept at atmospheric pressure...

Thanks!

 

Long story short:

-lexus canada approved short block replacement
-car was in a million pieces
-it's been almost 10K km since the short block replacement
-engine has not blown up and feels good and strong....

now here's the bad part...

-engine still continues to consume oil
-it does appear to be less
-after three checks it appears to be around 1.0L to 1.5L for every 2K - 3K km
-after first check again I chalked it up to break in
-by the third check at around 8K km consumption was not trending in the right direction and still high at 1.0 to 1.5 L
-lexus should have replaced the entire engine; not this piecemeal replacement nonsense
-more of my time will be wasted dealing with this issue in the spring
-I believe there is still a problem with the valve train as consumption is still high
-then winter came and even the old engine did not consume oil under light engine load for winter driving
-to be continued late spring early summer under summer driving conditions

wolfman

 

Keep in mind, the pressure reading will depend on many variables beyond your control including the accuracy of the gauge, current barometer, altitude, and ambient air temperature. The most important thing is consistency from cylinder to cylinder assuming there is no obvious damage to the bores.

FWIW, I am not a fan of compression testing. I like leak down tests much more because they will tell you where your issue is (valves, rings, head gasket, cracked head, etc.) and a compression test only tells you there is a problem.

 

How did you break in this new unit?

I would not accept that rate of consumption as normal in an engine I built.

 

Sorry for the late reply. In terms of braking in the new short block, the break in was done on the firm side. I don't believe in gently breaking in an engine. On the other hand, I don't believe hitting redline constantly during break in is the right way either. I generally do the following:

-do not drive at constant high speed and/or high rpm
-vary load on piston rings as much as possible
-load up engine firmly for 2 to 3 runs then allow for a cool down period; and repeat multiple times
-try not to get stuck in traffic; race track might be ideal for break in under none racing conditions
-do not lug engine; do not race engine aggressively
-allow for proper warm up of engine; coolant, engine oil, transmission oil