Squealing noise in engine bay '03 GT Turbo

[jimbrumgard]

I have recently acquired a 2003 PT Cruiser GT. About a week ago I made a hard acceleration, enough for the turbo to punch up the horses and when I backed off the throttle, a squealing noise began. The squeal is more obvious at an idle, but will drop off to nothing if you accelerate moderately. When you reach a cruising speed, the squeal/whistling becomes noticeable again.

At first I thought some vacuum hose had cracked or a vacuum operated device had popped a membrane. The noise seemed to be most noticeable at an idle, or at cruise, when there should be a high level of engine vacuum. So far no cracked vacuum hoses have been found.

Using an improvised stethoscope, I have located the noise to be at the cam position sensor (CPS). There is crankcase hose connection that comes off a nipple just aft of the CPS, but removing this hose shows that the squealing noise is not related to the hose or the nipple on the valve cover. Definitely in the sensor.

What can be squealing in a cam position sensor, or the magnetic target attached to the end of the cam shaft? Perhaps fore and aft shifting of the camshaft within the head?

I haven't tried to change the sensor as it has no moving parts, but may do so just to inspect the sensor to see if there are signs of the magnetic target rubbing the sensor.

Thoughts?

Jim

[jimbrumgard]

Just an update on my investigation on the squealing noise. I pulled off the cam position sensor to check it out. Nothing unusual was observed. the target magnet seemed uncracked and tight on the end of the camshaft. Not sure if the ribs on the magnet indicate any rubbing.

[chuzz]

I've never heard of something like that, but with a car, anything is possible. Have you checked it since you put the sensor back in and does it still squeal? Maybe check your air filter box and make sure one of the clips isn't broken. IDK, I'm not a mechanic. Just shooting for an idea.

[jimbrumgard]

Originally Posted by chuzz

I've never heard of something like that, but with a car, anything is possible. Have you checked it since you put the sensor back in and does it still squeal? Maybe check your air filter box and make sure one of the clips isn't broken. IDK, I'm not a mechanic. Just shooting for an idea.

Charlie,

Thanks for posting your reply. My airbox is alright, clips good, etc. Putting the cam positioning sensor back on and restarting the engine did not make a difference. The squeal was still there. It was also intermittent as well, loud after restarting then it quieted up. My latest theory is it may be a problem with lube getting to the 6th journal of the intake cam, which lies just behind the cam position sensor. I intend to tear down under the valve cover and inspect the cam bearing cap for evidence of galling. Bummer if that is the problem. Probably will need to replace the head and cam.

[chuzz]

That's the next logical step, man. Maybe you'll luck out and find a small burr of some type and be able to clean it up with some emery cloth. Before I'd replace the head and cam, that's what I'd try, but I'm NOT an ASE certified mechanic.

[jimbrumgard]

Just want to give everyone an update on the problem I had with my 2003 GT Turbo. The shrill squealing noise was probably better described as a whistle. I found it to be originating from the right end (drivers side) end of the head. But a more close inspection showed it was not from the cam position sensor, but slightly to the left, at the end of the lower intake manifold. Spraying some starter fluid on to the manifold while the engine was running caused the noise to change pitch and briefly gurgle.
When replacing the intake gasket, it was discovered that the previous owner had someone do a poor job of changing this gasket once before. They did not scrape off all the old gasket at the number 4 intake port. Because of this, the gasket could not be torqued flat between the manifold & the head, and it let loose when I started a hard acceleration, and the turbo did its boost thing, one time too many.
Also did a plug and wire change, as well as installed a new thermostat (old one stuck open and the engine took too long to warm up in the winter. Probably will get better gas mileage now. Nice to have it appropriately quiet and not doing an imitation of a tea kettle!

[chuzz]

Thanks for updating us, man. I hate it when people come looking for help and never let us know if suggestions helped or not. Stick around, man. You own a PT. You're going to need help from time to time!

[_PTGT03]

Originally Posted by jimbrumgard

Just want to give everyone an update on the problem I had with my 2003 GT Turbo. The shrill squealing noise was probably better described as a whistle. I found it to be originating from the right end (drivers side) end of the head. But a more close inspection showed it was not from the cam position sensor, but slightly to the left, at the end of the lower intake manifold. Spraying some starter fluid on to the manifold while the engine was running caused the noise to change pitch and briefly gurgle.
When replacing the intake gasket, it was discovered that the previous owner had someone do a poor job of changing this gasket once before. They did not scrape off all the old gasket at the number 4 intake port. Because of this, the gasket could not be torqued flat between the manifold & the head, and it let loose when I started a hard acceleration, and the turbo did its boost thing, one time too many.
Also did a plug and wire change, as well as installed a new thermostat (old one stuck open and the engine took too long to warm up in the winter. Probably will get better gas mileage now. Nice to have it appropriately quiet and not doing an imitation of a tea kettle!

just to let you know in technical documentation the 'left side' is the drivers, and 'right side' is the passenger. no matter which direction you're looking at.