4.0 SOHC won't start after top timing chain tensioner change

[Texan209]

So... I may have gotten myself in too deep but I thought I heard the infamous chain slap on startup the other day so I decided it was finally time to change timing chain tensioners. I'm very much a shade-tree mechanic, but I recently replaced my thermostat housing, so it's a pretty similar process to get to the tensioner. Unfortunately, everything is back together and the truck won't start.

I installed it dry but cranked the engine in "clear flooded engine" mode for several seconds a couple of times to build oil pressure before starting.
When it came time to turn the key, I got a few pops like it was trying to start, but it sounded pretty rough so I stopped cranking.

I have yet to hook up an OBDII to it, but I've rechecked the spark plug wires, vacuum lines and electrical connections, and it all looks correct. I'll re-check everything a third time with fresh eyes, but I'm operating on the assumption that it's all back together correctly.

This brings me to the question of - is it realistic that the timing moved on me during the switch? All I did was unscrew one tensioner (top drivers side) and replace it - truck didn't move or do anything that I would expect to change the timing, but here we are.

Has anyone heard of this before, or had a similar experience? From the research I did intially, it sounded like a pretty straightforward piece of maintenance.

 

[JJMaine]

You only did the front tensioner? If so maybe the passenger rear was the one that went out and that allowed the chain to skip a tooth? Hopefully not and you get it figured out soon.

I wouldn't think removing a tensioner and replacing it without running the engine would let it jump time.

I would put a ratchet on the crank bolt and rotate the engine by hand a few good revolutions to make sure nothings making contact that shouldn't be. Beyond that I'm not sure as I'm new to this as well but I'm sure some others will stop by to offer advice. Good luck sir!

 

[JJMaine]

One thing I was wondering about when doing my engine is how long it takes the new tensioners to build pressure because spinning my engine by hand with new tensioners, the tensioners don't have enough pressure (obviously with no oil in them) to keep tension on the guides and the guides move back and forth with the slack in the chain. The word is that they don't need to be primed though.

Makes me nervous when I go to "prime" my engine in a few days with the fuel pump relay out.

 

[Uncle Gump]

Did it run before you worked on it?

 

[Uncle Gump]

I think they can only jump time if the guides are busted up.

The tensioners go bad... let's the guides destruct... planets align... jumps time and seriously breaks stuff.

I did tensioners... didn't prime them... disabled fuel... crank a few times. Enable fuel... fire it up.

 

[JJMaine]

Awesome good to know thanks!

 

[Texan209]

Yeah, it ran before the swap, so it's gotta be related to wiring or the driver's side timing. I won't have time to pull it back apart until Sunday, but I'm thinking the guides just disintegrated and it skipped a tooth or two during the swap. I bought the truck with ~130k on it without knowing if they had been done before, so my guess is they hadn't.

I still want to re-check all the wiring (and the main ECU harness to make sure I didnt bend a pin while reinstalling - not that it felt like it, but it feels like a good thing to double check because my coolant gauge was broken before and now is showing cold temps on key-on)

Worst case scenario, the wife and I are parking outside until I source an explorer V8 and figure that one out...

 

[ekrampitzjr]

I'll bet you disconnected or damaged an electrical connector or wiring in the vicinity of the tensioner.

 

[morsetaper2]

@Texan209

So what was the resolution to this problem?

I changed my front tensioner today. Haven't run engine yet. As I'm in the middle of doing a thermostat housing replacement and it is still all apart.

As I understand it, when I go to oil-prime the new tensioner, hold the pedal to the floor then turn the key and let it crank. How long should I let it crank?

 

[JJMaine]

I'd pull the fuel pump relay personally. I've read reports where the "clear flood" method (holding the pedal to the floor) doesn't work and the truck starts and rev bombs to the moon. Not that it will happen to you but I wouldn't want to take the chance especially with timing chain tensioners not primed.

Before I started my engine after doing head gaskets I went by Uncle Gump advice and pulled the relay, and then cranked the engine a few times for a few seconds each time. Seemed to work great and on first start had no cam chain noise at all just smooth as silk.

Are you going to do the rear tensioner as well?

 

[morsetaper2]

I'd pull the fuel pump relay personally. I've read reports where the "clear flood" method (holding the pedal to the floor) doesn't work and the truck starts and rev bombs to the moon. Not that it will happen to you but I wouldn't want to take the chance especially with timing chain tensioners not primed.

Before I started my engine after doing head gaskets I went by Uncle Gump advice and pulled the relay, and then cranked the engine a few times for a few seconds each time. Seemed to work great and on first start had no cam chain noise at all just smooth as silk.

Are you going to do the rear tensioner as well?

Yes, I plan to do the rear as well. Just havn't got to it yet. I'm in the middle of replacing the thermostat housing. So while I had all that out of the way I did the front one. Figured I'd do one at a time. Rear is EZ to get to through wheel well on a warmer day.

Thanks for the info about pulling the fuel pump relay instead. Where is it located? Under the hood, under the dash? Weren't there also some relays behind the glove box, and/or pass side kick panel? My shop manual is out in the garage at the moment. And it's cold and raining. Not wanting to go out there :-(

 

[JJMaine]

Its under the hood in the fuse box. Drivers side up towards the windshield.