2010 5.7 Sequoia - I Messed Up...

I might have messed this one up good... looking for some help theorizing, please.

Ok, my wife's 2010 Toyota Sequoia Platinum has been rattling intermittently over the last couple years and I finally took the time to research that it's probably the driver's side timing chain tensioner (it was). I bought parts for it and took it apart last weekend. I discovered that the valley plate was also leaking coolant and that the cam tower was leaking on the driver's side. I decided to tackle all of these at once.

I am a pretty decent mechanic, but it's not my profession. Just know that I have worked on cars for 20yrs, which makes me knowledgeable, but not infallable. I'll admit that this job was about at the edge of my competence.

I replaced the 4 timing chains, the 4 timing chain tensioners, spark plugs, water pump and alternator along with seals along the way. I also resealed the cam tower, the valley plate and timing chain cover very well.

Long story short, I started it up today and it ran rough for about 20 seconds before it sounded like it let out a bunch of air all at once and blew a ton of dust (I am pretty sure) out from the engine compartment and then died. This was not a dark, oily plume of smoke, nor a sweet-smelling cloud like coolant. It seemed like just dust. It will not start again, though it turns over and seems to want to fire a little. I scanned for codes on a code reader and I am not getting any codes, so I am at a loss right now.

• Theory 1 - I messed up the engine timing (I was pretty meticulous, but it's possible)
  • What would happen in this case? Engine destruction?
  • Any way to confirm timing without tearing everything down again?

• Theory 2 - I took the secondary air injection valve apart and cleaned it pretty well with brake cleaner. This might have been a bad idea.
  • Would a failure of the secondary air injection system cause these symptoms?

Anything else you would look at?

 

You are way over my head, but you might want to post your story in the Ask The Toyota Mechanic thread. BTW, Welcome from LA (Lower Alabama)!
https://www.tundras.com/threads/ask-the-toyota-mechanic.2404/

 

I have nothing to offer here but maybe there is some insight to be gained from this video:

 

I'm shocked that no code was tripped running rough for 20min and then dying. Can you describe "running rough" in more detail and what brand/model of scanner did you use? I just did my timing belt on a 4.7L and it ran rough for a day or two but runs fine now. I even took it back apart to double check the timing marks and found it to be correct. I'm guessing it was the computer relearning the correct fuel/air ratios and idle speed timing.

 

There's only 1 source of compressed air in the whole engine compartment: secondary air injection pump. Well, engine itself is a giant air pump, but you can quickly figure it out if it has any extra hole in the block.

 

SAIS is only active during cold startup. I'd check these again as they're easy to get to. If they failed, then get a bypass kit from Hewitt instead of replacing.

 

The engine died in 20 seconds, it was a cold startup.

 

Exactly, and OP is worried he failed the SAIS system. If that's the case, a bypass is a relatively cheap/easy way to remove a variable and is far less than a replacement.

 

My understanding the OP is questioning if cleaning the SAIS valve was a good idea, but the culprit of "no start" is still unknown to him.

 

Here's my guess.......Since it was running before you replaced the chains and tensioners, and it only ran for 20 seconds, your cam timing might have been slightly "off" and the engine ran just long enough to eventually put an intake valve in the "open" position as the piston was in an upstroke, resulting in pushing the intake charge back through the intake plenum and out through the intake system...... Like I said, just guess. In any event, you will likely need to visually recheck your cam timing.

 

This ^^ seems probable as the VVT system would be making adjustments the entire time until it couldn't. That said, I would think it would making it closer to correct than more off.

Next step if it were mine, pull the plugs and do a leak down test following the firing order. If it bent valves, this will tell you that. But ya, being out of time and lighting the intake charge can reverse flush the air filter and split plastic manifolds.

PS - To start, place it on TDC for #1. You have a 50/50 chance it builds compression. Turn by hand and stop if it feels hung.

Was this new chains and and what literature did you use to do the install? Maybe we can collectively review it and see what might have gone wrong.

Hang in there...

 

I don't know what Denso ECU does, but Bosch does a VVT adaptation test when the engine is just started and reached some RPMs (1500 or so). If it detects an angle deviation beyond tolerated limit, it will not advance VVT, to prevent piston and valves interference. When my Volvo skipped a tooth on exhaust, the ECU disabled variable timing altogether.

Actually, when my older Volvo skipped not one, but 2 teeth on the crank, VVT was also disabled. That car was using a Denso ECU. Two teeth on that engine translate to 8 degrees, which is exactly an interference limit. Any VVT advance would destroy the engine.

So Tundra must be doing the same (testing VVT and disabling it if crank/cam angles are wrong).

 

Perhaps residual brake cleaner left in the AIS system ignited and popped a line? Now major vac leak? How well did it run for the 20 seconds it did run? Just throwing darts in the dark.

 

Did it make a hell of a rattle in those 20 seconds? These engines will set a check engine light almost immediately if the timing is off and lock out vvti

 

So, I was so bummed about this situation that I basically walked away from it for a month. I am back at it today, pulled the intake (which looks fine so far) and checked the valves through the intake ports. Nothing looks obviously damaged.

I am working on doing a compression test now, so I will get results of that posted here soon.

To answer the question about running rough - it did not make any serious rattles like pistons were hitting valves or any metallic noises, it just ran rough like cylinders were missing.

I was really meticulous about the timing, but I am not infallable. I re-checked it about 4 times before I put it back together. I used the information in this video - https://www.youtube.com/watch?v=oaDWBwmtVEE

 

I forgot to mention - the plugs are all out and they look good, no contact was made.

I am not getting any codes on the engine either, which is really weird to me. It didn't throw any codes and I checked thoroughly.

 

Ok, verdict is in.

I am not holding compression on the driver's side. Best cylinder on the driver's side is holding 130psi. On the passenger side, I am averaging 200psi.

 

Probable that the intake or exhaust cam timing is off on the driver's side, maybe just by one tooth. I had a similar situation when I rebuilt my 1GRFE and didn't get the intake gear on the dowel pin correctly, so the gear was slipping and compression was down on the entire driver's side. Engine ran, poorly, but didn't damage anything besides the intake cam gear.

 

How did you diagnose that?

 

I did a compression test, leak down test, then started disassembling my engine again starting with the driver's side until I looked at the cam gear and saw the marks from the dowel.

https://www.tacomaworld.com/threads...ed-machine-shop-recommendations.353600/page-4

 

I appreciate the info. I am going to start a leak down test now to see what that tells me.

Wife is not going to be happy.

 

Leakage tester is showing 70% leakage. RIP

 

That sucks, I know, don't let it wear on you, just concentrate on disassembly and inspection of the driver's side until you find the issue. Hopefully it's something simple and there isn't any damage.

 

I think pulling the engine is the only way to get down to the block to replace a head gasket or replace valves, right? If that's the case, it's probably time to throw in the towel. I am feeling pretty low about it all.

I can't hear where it's leaking exactly, but I am not getting bubbles in the coolant, and the intake valves look undamaged. I am suspecting the exhaust valves may have taken an impact.

 

You should be able to do most of it in the truck, I'm betting on a timing issue, which you can verify with the engine mounted in the truck...if you need to take the head off for any reason the engine can stay in for that as well.

If you take the spark plugs out, do you see anything out of the ordinary on the plugs? Covered in oil, or metal flakes?

With all of the plugs out, can you turn over the engine by putting a ratchet on the crank? Any strange noises?

If you drain the oil, and inspect the filter, do you see any metal debris?

 

Help me think through this for a bit - how could it be a timing issue causing the lack of compression? Is the hypothesis that maybe the exhaust valve could be open at TDC when I am testing the leakage? Would this be because the exhaust and intake cams are out of sync?

The plugs look fine, no damage, no flakes, nothing out of the ordinary. I can turn the engine over by turning the crank with a ratchet, no problem. No strange noises, they turn just fine.

I have not drained the oil, but I can do that and report back.

 

Either the intake or exhaust camshaft is slightly off from where it should be, so the valves are not closing at TDC. Mine did the same thing when I didn't install the intake variable Cam gear correctly, none of the cylinders on the driver side would hold compression, and leakage was huge.

 

Ok appreciate the info here.

I think I am going to start the leakage test and turn the engine over and see if I can find a spot in the cycle where I have acceptable leakage. The hypothesis is that if cams out of sync have the exhaust valves open or partly open at TDC, there is probably some point in the cycle where they are actually all closed and would have acceptable leakage. If I can find this, it would confirm your theory and would disprove a blown head gasket.

 

I agree with @armyoffoo hypothesis, if all cylinders on the driver's side have leakage at TDC then timing is probably off. If the head gasket was blown it'd be very odd if every cylinder had issues, and that goes for most head issues. If the timing is only slightly off I wouldn't think anything would have issues, even if it's an interference issue (not sure if the 5.7 is).

I know on my wife's 4.7 when I did the belt I had to do it about 3 times because it would jump a tooth. Did you turn the engine over multiple times by hand and verify the timing did not move before you reassembled everything? That is how I found the 4.7 timing was off since I'd spin the engine and the belt and cam teeth wouldn't align back to the same spot as I originally installed the belt.

 

On the 5.7, the teeth are uneven in number, so the timing marks on the pulleys only line up with the timing marks on the chain every like 40 or so rotations. That means that if you get everything correct, as soon as you start turning the chain around, it doesn't line up on the same marks starting on the next rotation, even if the timing is correct.

I am told that the 5.7 is an interference design.

Still planning on redoing the leakage test later tonight. I will update here with results.