Still ticking when cold after ...

[TilburyJam]

So I changed the oil and cleaned the PCV system about 300km ago.
And finished cleaning the sump and replacing the o-rings yesterday. I was pretty impressed with how clean the sump was.

And, it still ticks when cold on startup. I've assumed its always been a lifter noise.

So gurus, what do I check next.

Could it be the exhaust manifold gasket? seemed to be louder near the driver door than the front of the car, but could also be that it quietened as I moved to the front.

Will

[TilburyJam]

Oh, forgot to mention the car
2004 xc70 2.5T 208K(km)

Tried again this morning. Ticks quite loudly when you start up especially when the engine does it's own higher rev start up. once it comes back down to normal idle, its almost gone.

But if you stab the accelerator(up to 2000 revs) after its back at normal idle, (still cold) you will summon the ticking :-/
If you slowly increase to 2000, say over 3 or 4 seconds, the ticking wont be heard.

1)If I assume lifter noise
What difference to oil pressure and flow do you think slowly increasing the revs has? I assume that slowly increasing the revs, allows the oil to increase its flow gradually, and keep up with the slowly increasing revs/lifter cycles.

But once the lifters are pressurized does the increasing oil flow/pressure play that much of a role in their operation?

2) If I assume exhaust gasket noise
What difference to exhaust gas pressure does slowly increasing revs or stabbing the accelerator have? I assume that slowly increasing the rpm allows the turbo to spin up equating to less back pressure hence the leak not being heard. But when stabbing the pedal, the sudden increase in exhaust gas flow has a slow spinning turbo to overcome, causing the exaggerated leak/tick.


Will

[Tahoe_XC]

Do not rule out a cracked manifold... Grab a mechanics stethoscope and listen. Our 04 had similar issue after getting rear ended. Loud on cold startup that then went away as engine got warm.

[TilburyJam]

Thanks Tahoe_xc

I'll check that out

[Astro14]

Cold tick on my XC was an exhaust manifold leak. Went away gradually as engine warmed....gone after 30 seconds. Fix was a new gasket.

[hoonk]

2004 xc70 2.5t 208k(km)

1)if i assume lifter noise

but once the lifters are pressurized does the increasing oil flow/pressure play that much of a role in their operation?



That engine should have solid lifters, they do not "pump up" or get "stuck" partially compressed like the older cars with hydraulic lifters.

[TilburyJam]

So does that mean the ticking can't be between the lifter and the valve?

[hoonk]

The early engines 1991-1999? used hydraulic lifters. Those lifters could make noise if the oil was low or stick due to poor quality/lack of oil changes, or sometimes just never "pump up" due to constant low rpms. The only way solid lifters can be noisy is if they are way out of adjustment or have physical damage to the cam or lifter surface. The out of adjustment looseness won't go away by running the engine for a couple of minutes (yes there is a slight amount of thermal expansion). There is no easy way to check and adjust valve clearances - but it can be done.

[TilburyJam]

I'm learning lots, and fast, about this car. Thank you all so much.

This afternoon I used a piece of garden hose to listen behind the engine on top of the exhaust manifold, and it seems like an exhaust leak is the culprit. Even after the ticking had stopped, I could still hear it with the hose above the exhaust port of the transmission side cylinder.

I have another sound which you can only hear when accelerating under loud, ie in gear. It doesn't occur when reving in neutral, or cruising on the highway. It sounds like a chchchch crossed with a hissing sound. Do you think this could be the same exhaust manifold leak manifesting differently when warm and under loud.

Or do you think its unrelated?

Will

[RockitShip]

I would be surprised if you had an exhaust manifold leak and it didn't show a code such as running lean, or something to that effect. A smoke test should show an exhaust leak I would think. Did you try using a heavier grade motor oil?

[TilburyJam]

My front o2 sensor is dead. There is a code saying signal missing. So that would explain the lack of code being caused by the exhaust gasket leak?

I just recently changed the oil and used 5W30 Valvoline syn power mst. do you think I should go to 5W40? I'm planning on doing a short interval on the current 5W30. So could go to the 5W40 relatively soon. How would the heavier grade help?

And how do I do a smoke test?

Will

[RockitShip]

The heavier grade might help if it's just valve noise and the conditions are too hot. I see you are from s. Africa and assume it gets hotter than the northeast where 5w30 works ok, but trying a 10w30 or 10wXX may help (or not).

A smoke test is kinda what it sounds like. A mechanic will use a device that that produces smoke and has it run through the intake looking for signs of a leak such as the exhaust vacuum lines etc.

[rcdishman]

Just bought a 04 XC with 84000 miles last week and have noticed the exact same cold start-up tick symptoms as mentioned in this thread, any other advice on this issue would be appreciated, especially if you have had the same type tick and solved problem. Car runs great after a couple of minutes warming up, going to change oil this weekend and possible add some Lucas oil treatment (the Lucas additive seemed to help my older V70 tick). Anyways, any advice would be greatly appreciated, thanks.

[Astro14]

Had the tick. It was the manifold. Unless you're under the hood with the car running, you can't tell...From the driver's seat, an exhaust tick sounds a lot like lifter tick...

I fixed mine...without oil changes, miracles in a bottle, or other guesses.

Correct diagnosis is key before you go throwing guesses at a noise.

[RockitShip]

Changing the oil weight is a way of diagnosing. Besides diagnosing is still guessing just using careful examination.

[Astro14]

In cars in which I've I had a lifter tick, oil viscosity made no difference...