I blew the head gasket on the 31 model 42 conv. cpe. I had a marginal head on the car, and it blew the gasket. While apart, we decided the car should have a valve job, the engine having been done in the 1960’s. Put it together, started, ran beautifully but upon hard acceleration, a loud whistle or squealing noise comes from under the hood. (why me?) I have eliminated fan, water pump, etc. by disabling them and still being able to effect the noise. Various theories: intake manifold, exhaust manifold (I doubt this, no burn marks) vacuum line, (there’s only one, I plugged it, noise still there) Someone said head gasket, if it is there is no sign of a skip or, water, or bad running. Your thoughts and experiences, please. I figured if it was some sort of leak, I would let it sit over the winter and see if it plugged itself: this probably being wishful thinking. I appreciate your opinions, experiences, etc. Tony
Although noises are notoriously difficult to describe and to diagnose by e-mail it’s probably valid to first check those components mucked with during the most recent operation, i.e., the valve job.
“Squeal” vs. “whistle”: I tend to think of a ‘squeal’ as a mechanical noise from a fan belt or a dry bearing such as in a generator or fan hub, but a “whistle” as usually from an air leak.
To distinguish between the two, see if you can make it happen with the car in a static position at idle by snapping the throttle–or is a load required such as when underway?
A ‘squeal” from a bearing or belt might be found with a mechanic’s stethoscope or an improvised one made from heater hose or a broomstick (sometimes better than the real tool). If you can duplicate the noise with the car at rest, momentarily run the engine with the belts removed–but you’ve done that. So it may indeed be more of a whistle.
A ‘whistle’, especially under the conditions you describe, would lead me to attach a vacuum gauge to check the intake manifold joints, and the carburetor-to-intake manifold gasket, and other plugs and fittings in the manifolds–including the port to which you’ve attached the vacuum gauge. After noting the initial reading, spray a light oil over those joints/connections and watch for an improvement in the vacuum reading.
You might try a combustion gas detector in your radiator filler neck with the engine running. I have the kind (made by Cal-Tech, about 10-15 years old) that uses a proprietary blue fluid which turns green after a 2-minute exposure to combustion gases in the coolant, which would indicate a head gasket leak or cracked head or block (heaven forfend!)
Good luck, and please keep us posted!
To add something else to check, remove the air cleaner from the air horn on the carburetor and see if you affect the noise. There might be an obstruction in the lower section.
When ever I have a strange noise in my Pierce I am allways able to solve it by throwing Peg out of the car. ( I usually slow down first, the noise in the car goes away but then there is usually a very big one again when I pull into the driveway.) LOL
I once found the source of a whistle to be an incorrect carb-to-manifold gasket. If you disturbed the gasket during your work, I would suggest checking there.
Eddie: Please send me Peg’s Email address so I can share your levity with her. We taped the gasket on the carburetor, no change. The noise can be created by very hard acceleration while parked. I doubt the air cleaner solution because the problem began immediately after the valve job, and did not exist before.
Although we could try George’s suggestion with the vacuum gauge, I don’t think the leak occurs until the condition of “pull” while driving, or extreme acceleration while parked.
The coolant test sounds like the next move. Stay tuned. I am leaving it alone until I get back from Florida, in the spring. Maybe the damn thing will rust closed. Thank you all. Tony
First, let me correct my previous info on the combustion leak detector: It is actually Cal-VAN “Leak Check” for detecting combustion leaks, part no. 560, by Cal-Van Tools, Div. of Chemi-trol Chemical Co., 1500 Walter Ave., Fremont OH 43420. It consists of a clear heavy plastic cylinder containing proprietary blue fluid connected by a rubber hose to a rubber stopper. There is also a rubber squeeze bulb at the cylinder end. The instructions say to test on the engine both cold and warmed up. Extra bottles of fluid are Part no. 560-1 and I recommend buying at least one extra bottle.
Second, the more I think about the problem, the more I think that it is an intake leak which becomes apparent to the ear only when the engine is trying to pull in maximum quantities of air–although the leak may exist even at idle, which is why the vacuum gauge + aerosol oil test is still valid. One idea that comes to mind is to re-tighten the manifold nuts while engine is cold, making sure you’ve done ALL of them. Another thought is that if you used one of Fran Olson’s composite-only (no metal covering) manifold gaskets, be advised that he is now selling only metal-sandwich manifold gaskets for Pierce 8s because of performance issues experienced with the composite-only gaskets. New metal-sandwich ones are about $63 each. I bought a few in August and have installed one on my 1934 with perfect results. That car had an Olson composite gasket but the front exhaust port end blew out, and the rear (# port was on its way as found by examination when the old gasket was removed. And the nuts had been snugged by me several times on general principles before the gasket blew out.
You might consider checking vacuum gauge readings before & after snugging the manifold bolts.
Enjoy Florida, Tony!