Knock / Tick in the engine

[Koumar573]

Hi guys,

I have a 2008 Ford Explorer XLT with 130,000 miles. I am hearing a significant tick/knock from the engine bay that I cannot trace. The oil was just changed, but it was making this noise before the oil change. We looked at the oil that was drained and it was in decent shape, with no major issues. It had some slight debris in there but nothing that wasn't to be expected for a truck with that mileage. I am not experiencing any loss of power with the truck even under full load. My mechanic stated he thought it could be the dreaded timing chain but after driving it said he didn't think that was it. The tick is consistent and accelerates when the vehicle accelerates. I am not driving it until I can figure out what's wrong. Any ideas for what the next thing we should be looking for would be appreciated.

Thanks!

 

[boominXplorer]

$5 says you have a broken exhaust manifold stud, very common in these trucks

 

[fritz24]

Advance or Weak spark, unburned fuel and air in the combustion, incorrect oil viscosity or cylinder leak will cause you a knock, detonation and ping. Pull some plugs and see if its fouled with oil. If it is, check the compression.

 

[BootyDo]

Don't want to thread jack, but was just about to post a similar issue. I have a tick that seems to be coming from the passenger side. Two oil changes later using 5W-20, (I have the 4.6), and no luck. I've heard everything from a lifter to a cam position sensor to a bad flap in the IMRC. Before digging out any more funds/time, I figured I'd eliminate one of the suspects: the IMRC. Apparently with the car running, you just pull the intake hose. If the noise stops, you've isolated it. For the life of me, being green behind the ears, I'm not sure which hose is what and don't want to go randomly yank stuff from a running car.

Any insight?

Btw Koumar, does your tick increase with rpm or go away after warmup?

 

[Koumar573]

Btw Koumar, does your tick increase with rpm or go away after warmup?

Yes it increases with acceleration and no it does not go away after warm up, it is constantly there even at idle after warming up and gets faster on acceleration.

 

[BootyDo]

Yes it increases with acceleration and no it does not go away after warm up, it is constantly there even at idle after warming up and gets faster on acceleration.

Really sounds like whatever it is, we're dealing with the same thing. Or it could just be coincidence. From everything I've ready, the exhaust leak was very common on these cars but if I understand correctly, it goes away after warmup.

Does anyone know how bad it is to pull an intake hose on a running engine that feeds into the IMRC? That sounds like it would eliminate the little runners as a suspect before pulling plugs, (which if you haven't done could be a nightmare). And for what it's worth, I swapped all my plugs and coils maybe like a year before I got this symptom.

 

[Koumar573]

Now the mechanic says it may be the timing chain tensioner, rather than the chain itself, he's not sure yet until he can really dig into it.

 

[Koumar573]

He looked at the tensioners today, they were bad, he replaced them, but the noise did not go away

 

[Explorer_PL]

What engine ?

 

[Koumar573]

The 6 cylinder

 

[Explorer_PL]

Not really an expert on the 4.0. I asked since I just rebuilt the timing on my 4.6 and overall the tensioners were probably in the worst shape. The chains, phasers, and the guides were OK.

 

[Tech By Trade]

Pull the valve covers and see what kind of shape the upper guides are in. My guess is they are actually laying in the oil pan.
If you are a ninja like me you can have the intake and the valve covers off in 10 minutes flat. If not its an hour job.

 

[Koumar573]

Update: the valve covers came off and as suspected the tensioner that cannot be accessed easily is busted. My only recourse is removing the entire block to get to it... Shop has quoted $2000 so far... What a start to my weekend