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Discussion Starter #1
Hi all,

  • I performed a compression test a few weeks ago and found that cylinder 3 tested out at 115. When I added about 3mL of oil and retested 2 different times with pretty long cranks, it never got above 120. This leaves me too believe there is an issue on the top end. I've started to take the head off. I am currently working on the intake side and have noticed a decent amount of oil that has built up in the intake plenums. The Y plenum actually had a slight little pool of oil where it connects to the mid plenum. Should I now consider an issue with three bottom end too? Also, while in tearing this apart, what extra stuff can I take off the car that won't throw a CEL or is something I can easily spoof? For context, I am hoping to use the car rarely on the street, and mostly for some track duty. Adding a couple pics of the plenum below? Also, any tips on general for taking the head off, and what I should replace? Thanks in advance!
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I had one cylinder as low as yours when i did my compression test after my head rebuild(bent valves previously). but the next morning i tried it again after i recharged the battery + reconnected the fittings for the tester and got 175 psi on that cylinder(while cold, engine was out of the vehicle). Cant hurt to recheck again with a recharged battery.

try a leakdown test if you have one available.

also if you do end up committing with taking the head off: new head gasket, arp head studs since oem head bolts are torque to yield(one time use), cam seals, valve cover gaskets
 

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The Y plenum actually had a slight little pool of oil where it connects to the mid plenum.
I would attribute some of this since the engine system has the PCV Valve. If you're not familiar with it, it takes excess engine oil and fuel that gets into the crankcase and filters it back up into the intake manifold to be burned off.

Ever since I installed an oil catch can (I have one of the cheap ones), I've noticed all that excess oil and fuel is being caught.
 

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Discussion Starter #4
  1. Thanks for the suggestion, however I compression tested other cylinders after testing cylinder 3 twice (once with oil), and cylinders 4, 5, and 6 got up to 175, 175, and 181 respectively. I ended up retesting cylinder 3 again with oil the next day and it still maxed out at 120 which was the longest crank of all cylinders and the crank still sounded pretty healthy from a battery perspective.

    Thank you for the other recommendations! Do you have any recommendations about the process of pulling the head off, or any other recommendations of things that I can remove from the engine bay area that will make it easier to maintain\clean it up. I am thinking of doing the following: removing the ACIS contraption in the pic above, EGR blockoff plates, and possibly removing some of the EVAP stuff, but I am not exactly sure what I can do there without throwing CELs.



  2. I had one cylinder as low as yours when i did my compression test after my head rebuild(bent valves previously). but the next morning i tried it again after i recharged the battery + reconnected the fittings for the tester and got 175 psi on that cylinder(while cold, engine was out of the vehicle). Cant hurt to recheck again with a recharged battery.

    try a leakdown test if you have one available.

    also if you do end up committing with taking the head off: new head gasket, arp head studs since oem head bolts are torque to yield(one time use), cam seals, valve cover gaskets
 

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Discussion Starter #5
I would attribute some of this since the engine system has the PCV Valve. If you're not familiar with it, it takes excess engine oil and fuel that gets into the crankcase and filters it back up into the intake manifold to be burned off.

Ever since I installed an oil catch can (I have one of the cheap ones), I've noticed all that excess oil and fuel is being caught.
Thanks! I was thinking about that too, it just seemed like a lot. After thinking about it a bit more, I am wondering if it is possible that the oil I put in cylinder 3 for the wet compression test ended up pushing up through the PCV and back into the intake?

What brand oil catch can did you go with?
 

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  1. Thanks for the suggestion, however I compression tested other cylinders after testing cylinder 3 twice (once with oil), and cylinders 4, 5, and 6 got up to 175, 175, and 181 respectively. I ended up retesting cylinder 3 again with oil the next day and it still maxed out at 120 which was the longest crank of all cylinders and the crank still sounded pretty healthy from a battery perspective.

    Thank you for the other recommendations! Do you have any recommendations about the process of pulling the head off, or any other recommendations of things that I can remove from the engine bay area that will make it easier to maintain\clean it up. I am thinking of doing the following: removing the ACIS contraption in the pic above, EGR blockoff plates, and possibly removing some of the EVAP stuff, but I am not exactly sure what I can do there without throwing CELs.



Tips for removing the head:
Loosen the camshafts evenly in small increments, The shaft can snap if you dont. Also the socket needed for the head bolts is noted wrong on the fsm. Once you pull the head it's good practice and recommended to get it resurfaced before reinstalling.
Also my suggestion is to set the engine to 60 degrees btdc before pulling the timing belt and cams. Makes reinstall simple and prevents accidents.

Unsure what stuff you can pull without getting a CEL.

What was the reason for the compression test? Was the engine misfiring or acting weird?
 

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Discussion Starter #7
Tips for removing the head:
Loosen the camshafts evenly in small increments, The shaft can snap if you dont. Also the socket needed for the head bolts is noted wrong on the fsm. Once you pull the head it's good practice and recommended to get it resurfaced before reinstalling.
Also my suggestion is to set the engine to 60 degrees btdc before pulling the timing belt and cams. Makes reinstall simple and prevents accidents.

Unsure what stuff you can pull without getting a CEL.

What was the reason for the compression test? Was the engine misfiring or acting weird?
Do I have to pull the cams out while the head is on the block? I figured I would be able to remove the head bolts while they were still in.

I originally ran the test due to burning oil, and generally checking out the health of the engine since the test is pretty easy. After running the compression test, I did notice a miss at higher rpms, but that may have been due to me not being very meticulous about ensuring the coils\plug wires were really well attached.
 

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Do I have to pull the cams out while the head is on the block? I figured I would be able to remove the head bolts while they were still in.

I originally ran the test due to burning oil, and generally checking out the health of the engine since the test is pretty easy. After running the compression test, I did notice a miss at higher rpms, but that may have been due to me not being very meticulous about ensuring the coils\plug wires were really well attached.
Sadly on these engines the camshafts are in the way of the head bolts.

Also check out papadakis racing 2jz engine teardown on YouTube. It'll help give a good visualization and useful tips
 

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Thanks! I was thinking about that too, it just seemed like a lot. After thinking about it a bit more, I am wondering if it is possible that the oil I put in cylinder 3 for the wet compression test ended up pushing up through the PCV and back into the intake?

What brand oil catch can did you go with?
It's possible that's where a decent portion is coming from; however I would be careful and make sure the overall health of the engine is still in good condition.

I just bought on of the cheapo chinese ones, they're on amazon for $25 or so. It works, albeit probably not as well as one of the fancy ones that do extra filtering.

But I would recommend it since it helps increase fuel octane indirectly!
 

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Discussion Starter #10
It's possible that's where a decent portion is coming from; however I would be careful and make sure the overall health of the engine is still in good condition.

I just bought on of the cheapo chinese ones, they're on amazon for $25 or so. It works, albeit probably not as well as one of the fancy ones that do extra filtering.

But I would recommend it since it helps increase fuel octane indirectly!
Do you have any recommendations on how to check the health of the bottom end, or do I need to go guy a leak down tester? Thanks!
 

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Do you have any recommendations on how to check the health of the bottom end, or do I need to go guy a leak down tester? Thanks!
The only thing that comes to mind is if you're burning excessive amounts of oil. Now you said only one cylinder is down, so it may not be excessive. But if you're burning more than say, a quart of oil every 4000 or so miles (about what mine does with near perfect compression @ approx 1/4 million miles) then it could be worn rings.

Another way to check is by examine the spark plugs. Clearly you've removed them for the compression test. So what did they look like? Were they dry but black from normal carbon buildup? Were they more white? If cylinder 3 was more "wet" then the others, it could confirm what I mentioned previously with worn rings, meaning oil is getting into the combustion chamber.

If you have the tolerance to go with tearing the bottom end apart, it's a great opportunity to get some quality rods, pistons, and rings. If not for boost later down the line, then you'll get superior reliability.
 

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Discussion Starter #12
I had one cylinder as low as yours when i did my compression test after my head rebuild(bent valves previously). but the next morning i tried it again after i recharged the battery + reconnected the fittings for the tester and got 175 psi on that cylinder(while cold, engine was out of the vehicle). Cant hurt to recheck again with a recharged battery.

try a leakdown test if you have one available.

also if you do end up committing with taking the head off: new head gasket, arp head studs since oem head bolts are torque to yield(one time use), cam seals, valve cover gaskets
Ok, running a leak down test. Did I do something wrong, or are the exhaust valves that bad?

 

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Ok, running a leak down test. Did I do something wrong, or are the exhaust valves that bad?


it is a bit tricky to find the right position where the piston is to the top while the valves are closed.

try the test on a known good cylinder and see if you can get it to the sweet spot. tester should have a gauge on it that shows leak percentage that is also color coded green yellow and red.
 

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I did go back and forth multiple times trying to find tdc; what a pita! However, if you see here, the cam lobes for cylinder 3 are up, so they should be closed and sealed, right? I could easily feel air rushing out. I eventually took out the tester because it was showing 100% loss and I couldn't understand how that was possible. Eventually ran it directly off the compressor so I could hear it better.

Theoretically, could I run the test with the Piston anywhere in the combustion stroke too, right?
 

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I did go back and forth multiple times trying to find tdc; what a pita! However, if you see here, the cam lobes for cylinder 3 are up, so they should be closed and sealed, right? I could easily feel air rushing out. I eventually took out the tester because it was showing 100% loss and I couldn't understand how that was possible. Eventually ran it directly off the compressor so I could hear it better.

Theoretically, could I run the test with the Piston anywhere in the combustion stroke too, right?
If both lobes are up. Then you may have a bent valve or one stuck. Did it happen all of a sudden?
 

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Both lobes are up. I suspect it has been this way since I bought the car. I have always felt like it was underpowered to some extent, also smelled pretty heavily like it was running rich.
 

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Discussion Starter #17
hey all, any recommendation for valves, seals, cams, etc. while I have all this stuff out? Is there a trick to getting the lower plenum out? Seems like a complete PITA?
 

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Stainless under cut valves would be good for an upgrade. As for seals just good quality. No tricks to the intake. As for cams. That would be all you. You know what you are doing with the car in the future. If doing cams, remember to do springs and do the correct lash.
 

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Discussion Starter #19
Can ARP studs go on while the block is still in the car? Will the head for back on? OEM head gasket or something else? Anyone have BC 264 cams? If so, are they worth the money? Anyone running headers they recommend? Thanks all!
 

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Can ARP studs go on while the block is still in the car? Will the head for back on? OEM head gasket or something else? Anyone have BC 264 cams? If so, are they worth the money? Anyone running headers they recommend? Thanks all!
Studs yes. Gasket will depend on what you are doing. Oem will work. Headers, the best are a ton of money for not much more gain than the Megan/DNA etc.. Witch depends on what you plan on doing. As for cams. Once again, depends on what you want out of the car.
 
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