Timing chain replaced...truck won't start!!!

80psi on #8?

 

Yeah....surprised me

 

She may be a tired motor. Personally I would get a leak down tester and test with that to see where it’s losing compression

 

Definitely a tired engine...but it was running before I replaced the timing chain... had a p307 code for a misfire...so we changed the valve cover gaskets and spark plug tube seals, plugs and coil packs...it ran good for a few days then threw the same code 307...I decided to change the injectors and do the timing chain...I have not been able to get it going...

 

Yes...with the way these engines are setup, multiple camshafts and timing chains, it's possible to have the timing off a tooth or two in the wrong direction and have it still operate...although poorly. I managed to do this when rebuilding a 1GRFE, the intake cam phaser wasn't seated properly on the cam shaft and was slipping when the engine ran, as a result it had lower compression on that bank of cylinders and didn't run correctly...luckily I didn't bend any valves or destroy anything other than the cam gear.

 

I would expect all the cylinders to be down on pressure on one bank if the timing chain was off. My guess is that low compression is the cause of the misfire and it's still an issue. You've just added a second problem which is causing the engine not to start. I'm guessing you are going to have to troubleshoot the sensors that you disconnected while doing the work. Check the wire harnesses to make sure you didn't accidentally damage a wire. It could be possible to see if a code scanning tool will show the sensor outputs while trying to start it.

 

The misfire was on the other bank #7....the low compression is on #8...I definitely need to get someone that has a good scanner over though ...I agree.

 

Chain timing on UR engines is complicated. Review this Toyota field training video to see if you missed anything:

https://www.youtube.com/watch?v=oaDWBwmtVEE

 

The compression on "good" engines should be 180psi+, manual says 189psi or higher...With an entire bank running that low, I would suspect timing being slightly off. What reference material did you use to remove and replace the timing chain?

Compression Check: Specifications
Standard ............1300 kPa (13.3 kgf/cm2, 189 psi) or higher
Minimum .............1000 kPa (10.2 kgf/cm2, 145 psi)
Difference ..........100 kPa (1.0 kgf/cm2, 15 psi) or less

That video is a really good visual aid, I found the below link with Toyota service manual for the 5.7L timing:

https://workshop-manuals.com/toyota...tion/service_and_repair/components/page_2136/

 

Here is a downloadable copy of the manual, with testing procedures for the sensors if needed:

https://www.tundras.com/threads/2015-service-manual.7436/#post-1505788

 

This is the live data...truck is just sitting with the key on not running. Does that 5 degree ignition timing advance for cylinder 1 have any relevance? I cranked it, and it zeroed out and when I stopped, it landed back on 5 degrees...input please...

 

When you had the front cover off did you take the crankshaft pickup ring off? Looks like a little sprocket missing a tooth, for the crankshaft position sensor, and did you put it back on? I’ve seen that, then the crank sensor can’t see crank timing and won’t start. Did you remove the cams at all? I’ve accidentally swapped the intake and exhaust cams on one bank, actually got the motor times and ran.... although it ran like dog shit! If memory serves me the timing marks for the left and right intake cams and crank should line up with the factory marks on the timing chains every 28 rotations. I couldn’t tell you how many rotations for the left and right bank small chains that keep the intake and exhaust cams timed with each other. I can tell you though that it’s really ready to get them not timed correctly, 1 or 2 teeth off on either cam gear but still be able to time the intake cams with the big chain. Make sure your cam sensor connectors aren’t crossed. Cleaning the sensors shouldn’t have done any damage, I’ve brake cleaned and solvent tanked them plenty of times, just made sure they were dry before connecting.

 

I dont recall taking off a crankshaft pickup ring...cams did not come off...just the gears...if you look at the photos, we hand cranked the engine until the timing plates all lined up with the timing marks. We then removed and replaced. Can sensors are right. I've checked them multiple times...put a multimeter on them as well...As loose as that chain was, I am wondering if the chain had skipped a tooth before we took it off...does the 5 degree ignition timing advance for cylinder 1 tell us anything?

 

Repair Manual ignition timing spec shown below. Your data appears slightly out of range, but the spec is at idle. Personally, I don't think that's the problem, but idk. You need to focus on why one cylinder is at 80 psi compression. Minimum compression for a cylinder is 145 psi, with no more than 15 psi difference between cylinders.

Repeat the compression test on #8. An old school diagnostic trick is to inject a several teaspoons of engine oil into the tested cylinder just before cranking. If compression increases above the dry value of 80 psi, then gradually declines as the oil is lost, you have bad compression rings on that cylinder. Understandable after 350K miles. If there is no improvement in compression with the added oil, your valves are leaking off the compression.

After 350K good miles, it may be time to formulate a plan for your truck's future; i.e. donor engine, sell as-is, etc.

 

Can you post some photos of the fronts of the valve covers where the little plugs go?

 

My 2008 shows 5 degrees with the key on and engine off. Just as a point of reference...

 

Check for broken valve springs on #7 and #8.

 

I would try using a borescope and look into the #7 & #8 to see if your valves are in the right position at TDC closed and not bent. And also look for carbon that will hold the valves open. pickeledpigsfeet has a good idea look at the valve springs.

 

Valve springs look good. I don't have a bore scope. but, I had a local mechanic come by to listen to it turning over. He immediately said that the timing was off. Ok, so I tear it back down and rotate my engine by hand until the timing marks line up again. Once I did this, I stuck a screw driver down the #1 cylinder and achieved tdc. I took pics of it all attached.



Let me know what you guys thing.

 

I may be wrong but I don't think that would be wise. My dash lit up when I ran engine with one plug unplugged. I lost 4x4 and other stuff. Had to disconnect battery and wait. Luckly It fixed itself when I hooked it all back up.

 

Judging from the angles of the spark plug tubes and cam support frames in your first pic, I think you're sticking that screwdriver down the #2 hole. Cylinder #1 is the front cylinder on the driver side bank. Cylinders 1, 3, 5, 7 on the driver side; cylinders 2, 4, 6, 8 on the passenger side.

 

No, he is sticking it in cylinder #1.

 

You don't want to run it with no plug or no coil, you just let the plug fire while it's sitting on the valve cover to verify spark.

 

The manual says that the key should be pointing between 1 and 2 o'clock when the timing marks are down on the crank, your last picture looks like it's pointing at 6 o'clock?

 

I was going to send this yesterday but forgot to send and closed down computer
I am going to through this out there, is there a chance that you used #2 cylinder to time this instead of #1 cylinder? And or using the wrong valve position to set the cam timing? Also this would through off the spark timing. And if you set it to the wrong cylinder then the pistons would match the compression stroke but the spark would not be correct.

I agree with JohnLakeman! Because the whole scenario still sounds too me that the chains are set to the wrong cylinder.

 

He used the correct cylinder to find TDC, but from what I understand, the key on the crank timing gear should be pointing at Cyl No 1 when at TDC, in the last picture it looks to be pointing straight down.

 

Looks like the timing mark pointing straight down, if you zoom in can see the dot above white paint mark.

 

I've been searching a little more information on this, but this guy right here breaks it down barney style with engine marks, start and ocular pleasure everywhere, pretty much the whole 9 yards...

Edit: Mind the English... you may or may not need subtitles

https://www.youtube.com/watch?v=HYsVc1zGuYY

 

One video on installing the cam gears showed fitting them by hand and ensuring that they were all the way on and locked in before tightening down the bolts that hold them on.

I could see myself making that mistake!

 

UPDATE....

So I took the timing chains off and the cam phasers....Checked the angles on the cam shaft knock pins and one was off like 20 degrees....


So here is my question....should I go ahead and pull the heads off and check to see if there are bent valves since I have low compression on cylinder 8? Or assume that the low compression was because it was out of time and that correcting that will correct the compression issue? Thoughts....