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Booming noise over 60 mph in 71 1800E[ALL/1998] posted by Lance Gordon on
Wednesday, 8 October 1997, at 8:17 p.m.
I have an absolutely lovely '71 1800E that I have restored over the past 7 years. I'm really begining to truly enjoy driving it since I learned that sealing the fuel injector mounts to the head makes a great difference in how the car runs. I've also almost eliminated rattels and squeeks but have one remaining problem that really bothers me.
When driving the car on the highway, as soon as I reach about 60 - 65 mph, the car sets up a loud booming sound. Its as if the exhause sudenly became very loud. I've worried about it being all kinds of things, but wonder if it could be tuning. Can the timing cause the exhaust sound to be loud?
I've had the wheels and tires ballanced. I find no problems with the wheel bearings, I've had the transmission rebuilt, put in a new engine (fresh from Volvo) and put in a new exhaust system also from Volvo.
The noise doesn't seem to be very load related but mainly engine speed. While its mainly only a problem at highway speeds, I can also hear it when the engine is run much over 4,000 rpm in second gear (its an automatic).
At this point any ideas would be appreciated. Thanks, Lance
Re: Booming noise over 60 mph in 71 1800E[ALL/1998] posted by Glenn R. Goodspeed on
Wednesday, 8 October 1997, at 9:49 p.m.
My guess is that your exhaust system has a resonance at the frequency produced by your engine at about 4,000 rpm. I had the same problem on my '63 1800, and it lasted until I replaced the front muffler.
You can test my theory by seeing if the noise begins to decrease at speeds higher than 70 mph. Of course, you should only do this under appropriate sage driving conditions.
If you just replaced the entire exhaust system with a stock Volvo system, I would recommend trying aftermarket components. -Glenn.
Goodspeed's Volvo 1800 Newsletter
Re: Booming noise over 60 mph in 71 1800E[ALL/1998] posted by Stan on
Thursday, 9 October 1997, at 12:31 a.m.
Glenn,
I had a similar problem in my 91 240, but the booming noise was between 70 - 80 MPH. I had just replaced the exhaust system with the high flow system from IPD. Their suggestion was to remove the bracket in front of the first muffler, and that cured the problem completely. Now I have to replace the bracket with one that won't resonate, but that should be a minor problem.
While your problem may be a different component, it does sound like a similar problem, so you might start by checking your exhaust system. I would start by getting it on a rack and eye-balling the system to see if you can see anything that doesn't look right. If nothing is obvious you could try loosening or removing brackets individually and test driving the car. You should be able to isolate the problem in this manner.
Good luck with you search.
Re: Booming noise over 60 mph in 71 1800E[ALL/1998] posted by Jarrod on
Thursday, 9 October 1997, at 9:11 p.m.
Could it be your drive shaft?
Is the sound more to the center of the car? A kinda shot universal joint will generate a more subtle noise and only under certain conditions. A really shot one will be very dramatic.
Or how 'bout the centering (hanging) bearing? If the rubber is deteriorated (which acts as a harness) or even if the spring is off (will lead to deterioration AND is a common occurance) the shaft will bounce up and down making something more like hammering with a rubber mallet. The bearing could be shot itself too. If so, get a bearing and the mount from IPD (not your dealer). It costs only about $35 for everything. You will need to know the diameter of your shaft to order.
All of the above can show up under very specific driving conditions which could explain why it only happens at the higher speed.
Then what the hell do I know...really. Any mechanics want to back me up?
-jarrod
p.s. Some cool things are brewing behind the scenes. I encouarge everyone to try ichat paging". Give it a shot and start posting your handle in your brickboard messages.
My handle is: slonob.
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Re: Booming noise over 60 mph in 71 1800E[ALL/1998] posted by topi on
Saturday, 11 October 1997, at 6:37 p.m.
Try this: Drive speed you hear noise, then shift carefully to neutral. If noise goes away it's the motor. If not it's driveshaft center bearing or rearend. If it's motor weld a piece of stainless steel flex pipe before the front muffler. You find this flex pipe on almoust all Japanise cars. Good luck!