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Well, moving on. Was hoping for a bit of support from the collective but have a few other resources to draw from. Hopefully, this thread will provide some help to the next RX owner experiencing similar issues.
We have decided to remove the front head and are well into the work. Taking some pics for re-assembly. We have access to the FSM as well,
Once the head is off, we’ll have a good idea on how to proceed.
Before taking the head bolts out, please inspect the valve springs on that problem cylinder.
ZERO compression is more than likely a broken or stuck open valve.
Once you get the camshafts out, take the valve buckets off with shims on it. ( keep them in order )
You might find in line with a broken spring, bent valve, worn out keepers or just a broken valve.
I'm hoping for a broken spring or a broken keeper since its easier to replace w/ out taking the head off.
Before taking the head bolts out, please inspect the valve springs on that problem cylinder.
ZERO compression is more than likely a broken or stuck open valve.
Once you get the camshafts out, take the valve buckets off with shims on it. ( keep them in order )
You might find in line with a broken spring, bent valve, worn out keepers or just a broken valve.
I'm hoping for a broken spring or a broken keeper since its easier to replace w/ out taking the head off.
Good luck
Thanks, that's appreciated.
For sure, I will be sure to do inspections before removing the head bolts. Anything I can do without taking off the head would be preferable, along with keeping those buckets and shims in order.
Do these engines ever require a valve clearance inspection? I have to do my motorcycle every 20,000 kms.
I have not come across any suggestion to check it at the prescribed service intervals. Leading me to believe, that you let them be till the cam is removed.
Cams have been removed as per the FSM,
safely stored with caps in order. They are factory stamped with numbers.
bearings look good.
The valve “buckets” lifted out easily with a magnet. Also, stored in order.
Visual inspection reveals nothing obvious.
If the head has to come off, the most difficult part appears to be the exhaust manifold. Wondering if the two bolts connecting the manifold to the pipe might be the best option.
They will probably have to be replaced, I think.
Lol, I wish I could’ve gone quicker. Once I’m done I might get cold beer for a month or longer from my son!
Looking forward to that.
So, the plan:
Aquire spring compression tool and remove burnt valve. Expect to see valve seat damaged, but if not, replace valve.
Thinking I may replace everything else in the hole, too. Have to check for lash. Could’ve been a manufacturing defect but the damage may have affected the rest of the valve parts.
The other valves look good, though, and no big compression issues.
Might get get a new valve from Toyota, not sure yet.
Then, new gaskets, maybe head bolts. May do the knock sensors or harness or both. No codes for those have appeared but there they are, easy to service.
I would examine the head of the piston and side of cylinder. My experience is limited, but the burn of would be on the exhaust side. The only burn off I can think of on the intake is a pinhole to start and the owner just kept on driving.
Lol, I wish I could’ve gone quicker. Once I’m done I might get cold beer for a month or longer from my son!
Looking forward to that.
So, the plan:
Aquire spring compression tool and remove burnt valve. Expect to see valve seat damaged, but if not, replace valve.
Thinking I may replace everything else in the hole, too. Have to check for lash. Could’ve been a manufacturing defect but the damage may have affected the rest of the valve parts.
The other valves look good, though, and no big compression issues.
Might get get a new valve from Toyota, not sure yet.
Then, new gaskets, maybe head bolts. May do the knock sensors or harness or both. No codes for those have appeared but there they are, easy to service.
Skip the head bolts, you can still re-use them.
I know you never mentioned it overheating but slap a straight edge on it just in case.
Intake and exhaust seals on all cylinder of course. <-- a tool for this will save you time and grief. https://www.tooltopia.com/schley-923...yABEgL4jvD_BwE
Have cleaned up the garage/shop from all the disassembly rigmarole. Set up a bench for working on parts, ie. cylinder head/valves.
Found that I could not rent the proper valve spring compressor so went to Princess Auto and voila.
Watched a few videos on YT last night which were enlightening - especially the series called "Cylinder head 101" which continues through 109. This is a machinist showing his techniques for cleaning valves, lapping, dye and so on. I think I'll attempt to be a lapper for this project.
Also, got quotes from Toyota for parts. They want $50 for an exhaust valve. Better price than the $62 quoted from the local Lexus dealer. That's almost a six pack of beer.
Also, did a mock order on RockAuto for jobber parts. After the dust settles, I may order some Toyota and some aftermarket, ie NTN timing belt tensioner is also available on Amazon for a bit cheaper, as well.
But, for parts like the valve, oil seals and the like, I think I'll feel a bit more comfortable using the genuine Toyota parts.
Springs and head bolts are within spec according to the FSM and my vernier caliper.
The plan for today is to clean off those valves, clean the carbon off the combustion chamber, inspect and prepare for lapping. Also, going to throw a straight edge on the head and check clearance.
I'd like to find some decent cleaning solvent to use on this head - any recommendations?
Gunk makes a spray that looks decent.
I thought it was the intake valve that is broken. Could be the angle of the camera.
Salim
Indeed, it was.
After cleaning them, you can see the pitting on the intake valves from the exhaust valve metal. I have to take a closer look at the cylinder wall. Hope it’s okay.
06-02-19, 05:01 PM
