Another bad engine…

[CoCoCo4Runner]

I’ve owned my project 4runner since July, and have driven it once. I bought it cheap knowing it needed an engine, I’ve been busy with work and life so I haven’t had much time to mess with it. I finally got a used ebay motor, 2000 model year with 155k miles, was supposedly a good motor. I get it back to my workshop, do a leak down test and every single cylinder failed miserably. I could hear air rushing out of the exhaust/intake ports so this leads me to believe the valves are shot. What could cause every cylinder to exhibit this? I haven’t timed the motor myself but all the timing marks are dead on.

I’m at wits end here and extremely dejected over the whole situation

 

[rdruss]

Well, it still could be the cam timing is off. I would pull a valve cover for bank with no.1 cylinder and when you are confident the cam timing says it is on no.1 cylinder TDC, check your valve clearance, you should have some on both valves, if not, could be a timing problem. Look at the cam lobes too, they should both be on the base circle at TDC which is why you should have both valves closed.
If that checks out you could have an overheated engine with scored cylinders, which destroyed the ring seal.

 

[alumarine]

I have to ask.
Are you rotating the engine to the right spot so the intake and exhaust valves are closed for the cylinder you're checking?

 

[CoCoCo4Runner]

I have to ask.
Are you rotating the engine to the right spot so the intake and exhaust valves are closed for the cylinder you're checking?

Yup, I’ve done multiple leakdown tests on various engines, my technique is fine. Something is up with the valves and I can’t explain what.


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[brillo_76]

One thing I learned years ago is toyota heads can not take the heat. If your donor engine got hot. Possible warped head. I suspect one of 3 things. Warped head, timing off or rings gone.

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[mtbtim]

If you're sure you're getting each cylinder at top dead center on the compression stroke when doing your leak down test, it sounds like you got a shitty engine but maybe it's not too far gone to save. Pull the valve covers off and do a valve lash check and see where they're at. If you can bring them back in spec, you might find the compression numbers come up to good numbers.

I shot a Valve Adjustment video for the 5VZ-FE engine that will be coming out very soon. My buddy Wei had 3 cylinders with bad compression, 85-90 psi, and we were able to bring all 3 back to good numbers, 195-205 psi.

 

[3bears]

If you're sure you're getting each cylinder at top dead center on the compression stroke when doing your leak down test, it sounds like you got a shitty engine but maybe it's not too far gone to save. Pull the valve covers off and do a valve lash check and see where they're at. If you can bring them back in spec, you might find the compression numbers come up to good numbers.

I shot a Valve Adjustment video for the 5VZ-FE engine that will be coming out very soon. My buddy Wei had 3 cylinders with bad compression, 85-90 psi, and we were able to bring all 3 back to good numbers, 195-205 psi.

looking forward to another helpful video.

as far as original post...every cylinder to be bad ....going through the valves...to me sounds like a timing issue.

 

[Romeo1]

Oh come on now……Don’t be that way. Just fix it, move on, and enjoy the ride. Between the two engines you have, surely you can make one good one.

Everyone likes the idea of project vehicles, but the reality is not everyone is cut out for that life. Usually it’s a lack of time, money, or desire.

I kind of doubt that every cylinder fails leak down on your donor engine, but who knows it’s not impossible just unlikely.

The dumb questions to ask here are are you using a quality leak down tester? Did you verify that you are at TDC in each hole when testing was conducted? The piston does come up twice, I know it sounds stupid to say that out loud but I know a guy who did just that. Most engines have some overlap at the end of the power stroke where the valves, or at least one of them, are typically open a little.

Edit to add to what Tim said, you’re also assuming that the timing and the valves are correct on the donor engine. It may very well not be.

 

[Romeo1]

If you're sure you're getting each cylinder at top dead center on the compression stroke when doing your leak down test, it sounds like you got a shitty engine but maybe it's not too far gone to save. Pull the valve covers off and do a valve lash check and see where they're at. If you can bring them back in spec, you might find the compression numbers come up to good numbers.

I shot a Valve Adjustment video for the 5VZ-FE engine that will be coming out very soon. My buddy Wei had 3 cylinders with bad compression, 85-90 psi, and we were able to bring all 3 back to good numbers, 195-205 psi.

Looking forward to the new one. The videos never get old Tim. I’m over 3 decades in on spinning wrenches and I use your T4R videos all the time. The wealth of information you have compiled is just astounding.

If I had my way you’d be up for a Nobel prize. [emoji1690]

THANK YOU TIMMY!

 

[Devbot]

I agree with the others, there has to be a common denominator. I can see one cylinder being bad, but all 6? All reading within the same ballpark, that is almost impossibly low? That's a whole lot of unlikely things adding up. And if that one cylinder is reading 3x as high, I would think that's pointing to a timing issue at the least.

 

[Bad Luck]

I agree with the others, there has to be a common denominator. I can see one cylinder being bad, but all 6? All reading within the same ballpark, that is almost impossibly low? That's a whole lot of unlikely things adding up. And if that one cylinder is reading 3x as high, I would think that's pointing to a timing issue at the least.

How are you determining that the intake and exhaust valves should be closed?

EDIT: My bad Devbot. I thought I was quoting the OP and not you.

 

[mtbtim]

How are you determining that the intake and exhaust valves should be closed?

This is how I did it.

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[Bad Luck]

Yup, I’ve done multiple leakdown tests on various engines, my technique is fine. Something is up with the valves and I can’t explain what.


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How are you determining that the intake and exhaust valves are closed?