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Strange Noise  Rating:  Rating
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 Posted: 10-31-2014 06:37 pm
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Rick Willard
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Hey Folks,

I'm scratching my head on this one, so I'm asking for some expertise from my fellow club members....  My JH is a real nice one that I just acquired last month.  One of the small issues I knew would have to be addressed is that the car is making a strange noise that actually comes and goes.  I'll try to describe it well, but will field any questions from those of you who might have a theory.  This is actually my 4th JH and I thought I had pretty much heard just about every bad noise a JH can make.  However, this one is a mystery so far.

The noise I'm talking about is a low wallowing noise that I/we initially thought might have been some sort of dry bearing...oil sump?  timing belt tensioner bearings?  water pump?  clutch-related?  gearbox?.  But the pattern is strange.  When you get in the car and drive it, the noise is non-existent.  Once it gets warmed up, you start to hear this noise that follows the RPM's and will slowly get louder.  It does not follow the speed of the car, and it doesn't matter if the clutch is engaged or not.  It follows the RPM's of the engine.  One footnote, you especially hear this noise coming from the passenger side.

One of the initial theories we had is a faulty exhaust at the center resonator (loose baffle vibrating and/or expanding under heat). That theory has been dispelled after we installed a replacement exhaust system (bottom of headers to the tail pipe). The replacement exhaust system was virtually brand new, so we know that's good.

The strange thing is that you can be very frustrated listening to this noise, and then...even when the engine is still warm...it just stops and goes for several more minutes without any noise at all.  One of the theories we have is that the noise is possibly the sound of "air pushing through a tube."  We're pretty convinced that the engine and transmission are generally very solid (running with 45mm Dellortos) and the receipt file that came with the car would confirm that it has been very well kept leading up to my purchase. 

If anyone here has any initial thoughts, I'm all ears.  Again, have heard our JH's make many noises over the years, but this is one I've never heard before.

Thanks in advance for your time and insights!

Rick


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 Posted: 10-31-2014 06:50 pm
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Jensen Healey
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Hi Rick, I think you are right about the tensioner bearings and water pump. Maybe try some WD40 to see if the noise changes.

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 Posted: 11-02-2014 01:18 am
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Tom Bradley
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Sounds most like a water pump bearing to me. These can make all kinds of strange noises. It can also change depending on whether the thermostat is open, letting water through or not, which would explain it going away sometimes when the car is warm.

I suppose it could also be the thermostat itself.  If something has come loose, it could be making strange sounds when the coolant is flowing.

It does not sound like the cam belt to me, but you can rule this out by tightening it a bit and see if the sound is then present all the time.

You should be able to narrow down the location by driving the car until the noise starts and then parking it and using a tube to listen to various suspect spots around the engine.

Last edited on 11-02-2014 01:29 am by Tom Bradley

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 Posted: 11-02-2014 12:23 pm
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Jim Ketcham
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You can eliminate the water pump and alternator as sources by removing the fan belt during a noisy period. Obviously you will not have cooling so limit your operation accordingly.

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 Posted: 11-02-2014 12:46 pm
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Rick Willard
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Thanks for the input, guys. All of this makes good sense to me. By the way, Tom and Jim, you might be on to something. I didn't mention it before, but the alternator is showing signs that it is nearing end of life (voltmeter shows good charging with just the engine running, but the Ignition light surges on/off when the fan, lights, etc. are on). Using a solid tube to detect vibrations around suspect points on the motor has been suggested to me once before (will heed that advice). The temporary removal of the alternator belt might tell us about water pump/alternator. Glad to hear any other theories out there? Otherwise, will advise of the outcome when it's determined. Again, many thanks for the suggestions!

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 Posted: 11-03-2014 01:10 am
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Tom Bradley
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The electrical problem you are describing sounds more like one or more bad connections rather than the alternator itself. My experience with these alternators is that they either work 100% or not at all. But on both of the rebuilds of these cars I have done, I spent much time repairing or replacing electrical connectors throughout. Spade ends, like on the alternator, can usually be cleaned up with steel wool. If the connection is loose, the female ends on the wires can sometimes be tightened up with a pair of pliers. But most of the time I ended up cutting these off and replacing them. Many of the strands going into these connectors also get broken over time, so only a few strands are left to conduct the power. Also check the connections in the fuse box. In my current car, these were in seriously bad shape when I got it. Also check the ground connection between the engine and the body of the car. This can also get pretty bad, especially on the body end, but if the starter is cranking OK, it is probably OK.

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 Posted: 11-08-2014 02:53 am
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Rick Willard
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Hey Guys,

For any of you watching this thread, I'm still open to suggestions. Here's what I know....

* Engine has been thoroughly checked and there is agreement that the problem is not any of the things mentioned above. It is NOT the cam belt tensioner bearings, the water pump, the oil sump, etc. The engine itself seems to run extremely well, has great compression, etc. We ran the car briefly without the fan belt to eliminate the water pump and/or alternator as the culprit. The noise was still there. Mechanic (with 40 years of classic British experience, including the JH) checked all parts of the motor thoroughly with mechanic's stethoscope, and he feels that the engine is strong with no apparent issues.

* The noise starts at about 1,500 RPM's and is especially evident up to...about 3,500-4,000 before the noise of the engine drowns out the noise (if it is there at all).

* The noise is intermittent. It is not evident when it is cold. Once the engine is warmed up, you begin to hear it. Sometimes, the noise is not there at all, even when warm. The car was driven 20+ miles this morning in city and highway, and the car was perfect (no noise). Tonight, came back from a 10-mile freeway cruise and the noise was obvious coming on and off the ramps.

* The noise has a very similar tone as you rev the engine. In other words, when it starts at 1,500, it has the same TONE (low wallowing sound) as it does at 3,000, with just a higher intensity. It seems to be coming from the back of the engine toward the rear of the car. This might lead us to the clutch, throwout bearing, pilot, etc, BUT...the noise is the exact same whether or not the clutch is engaged and the (4-speed) tranny seems to shift pretty smoothly.

Any/all input is welcome. Thanks, everyone!

Rick

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 Posted: 11-08-2014 03:29 am
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Jensen Healey
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It's starting to look like the main bearings. As the block warms up and expands, the bearing tolerance widens.

What oil are you running? Hopefully a 20-50 with ZDDP like Valvoline Racing.

You could try some Lucas heavy duty oil stabilizer to see if it changes or eliminates the noise. If so, the mains need replacing.

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 Posted: 11-08-2014 04:01 pm
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Greg Fletcher
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I had a rear axel bearing on the way out once and it was making the noise you describe. It's a strange wallowing noise and it's nearly impossible to pinpoint while you're driving the car and it obviously varies with speed. If you're sure it's really engine RPM related, then that would certainly not be it.

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 Posted: 11-10-2014 06:15 pm
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Tom Bradley
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Does the sound change depending on the load on the engine? The only experience I had with bad main bearings (not JH), the sound was louder under acceleration. What is puzzling is that it comes and goes. Maybe excessive end float? If the crank shifts too much one way or the other, then the noise starts?

It could be the clutch, since the housing and pressure plate are bolted to the flywheel and so are always turning with the engine. I don't know what in the clutch would cause this type of noise unless a rivet has come loose or something.

I would rule out the throwout or pilot bearings: I have had both of those go bad: they sound like a high-pitched whine. Unless maybe the pilot bearing is completely destroyed and the transmission shaft is shifting out of alignment with the crank. This does not seem likely, though, unless you have been hearing a high pitched whine when shifting for some time.

Last edited on 11-10-2014 06:15 pm by Tom Bradley

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 Posted: 11-10-2014 06:39 pm
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Rick Willard
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Last edited on 11-10-2014 06:46 pm by Rick Willard

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 Posted: 11-10-2014 06:39 pm
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Rick Willard
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This is a very good question, Tom, and I'm sorry I didn't cover it with previous commentary. The noise is more obvious when there is NOT a load on the engine. In other words, as I'm slowing down, step on the clutch, and give the engine a slight rev in the RPM range I mentioned...that's when you REALLY hear this low wallowing noise. But even during acceleration, it's there. It's just not as prevalent with the engine/drivetrain building revs and speed. Again, the TONE stays the same, but the intensity changes with the engine speed.

One other bit of information. Last night I had the privilege of speaking with the owner who had the car from 1988 - 2012. He purchased the car with 32K documented miles in '88, did a meticulous cosmetic restoration, and only put 16K miles on it during his 24 years of ownership. He is CERTAIN that the odometer reading of 49K miles today is correct (owner from 2012-2014 only put 1,500 miles on it). He also confirmed that, while he replaced the head gasket once and did the oil pan gasket once...the engine has never been rebuilt. So...it's an awfully original example.

I'm certainly not dismissing the main bearing theory mentioned here (I am currently running Valvoline 20/50 synthetic with VVR). I just don't know for sure that it's the mains because I've had several folks with years of JH experience tell me that they just don't believe it's coming out of the engine at all. If it is a main bearing, I'm not too worried, as I have a 2.2 crank w/ bearings, oversized pistons, and bored out liners ready to go. This might be all the excuse I need to go forward with an upgrade. But honestly, I don't like just replacing parts to eliminate theories. I'd rather diagnose the problem with reasonable certainty, if I can.

Thanks again for chiming in here, guys.

Cheers!

Rick

Last edited on 11-10-2014 06:40 pm by Rick Willard

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 Posted: 11-12-2014 07:01 pm
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Tom Bradley
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I agree that a well-maintained J-H with such low mileage is unlikely to have internal bearing problems. So my next guess would be external parts which tend to degrade with time rather than mileage, such as the engine dampener, rubber engine mounts and rubber and plastic parts on the intake.

What is interesting is that the noise is greatest when revved with no load. This is the situation where the engine will twist the most. If you have the original Stromberg setup, one possibility is the hose between the airbox and the air filter is loose or has a slit in it which opens up when the engine tilts over.

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 Posted: 11-13-2014 12:11 pm
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Rick Willard
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Thanks again, Tom.

Did a quick huddle with the folks who have seen and heard this noise and we agree that it's not the mains. If it was, we would hear more of a rhythmical noise that would coincide with each combustion stroke as it loads the crankshaft. That doesn't fit this noise, so we'll eliminate that possiblity...for now.

Tom, you mentioned the airbox, and one of the descriptions of this wallowing noise is that it "sounds like air being pushed through a tube." This car has 45mm Dellortos with individual K&N filters for each carburetor (aftermarket). It also has a separate K&N filter for the separate tube running into the bell housing. We've run the engine with all these filters removed and it didn't change the noise. So.... Hmmmmm....???

The one thing that has been emphasized to me is that this is not a major thing. A couple of folks have said "sounds pretty normal to me for a JH..." We all agree that this noise is not not likely to lead to some catastrophic failure. However, having owned a few JH's before (with Strombergs and Dellortors) and never having this problem...it just bugs me.

Tom, thanks again to you (and everyone else) for your time. One way or another...we'll figure it out.

Cheers!

Rick

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 Posted: 11-13-2014 05:50 pm
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gmgiltd
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Hi Rick,
I would tend to go with Gregs suggestion - rear axle bearings. I have had a similar low intermittent rumble which varied slightly depending on load/overrun/corners and roundabouts.
After eliminating driveshaf, differential and brakes I am pretty sure it's the rear axle bearings on my car and will be replacing them as soon as the bearing retainers arrive.
Gordon

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 Posted: 11-18-2014 09:21 am
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gmgiltd
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Wheel bearing retaining bushes arrived from Delta yesterday (very good service) and the new bearings installed this morning. Brief test drive of 20 miles and it would seem that the rumbling noise has been cured.
Gordon

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 Posted: 11-18-2014 11:44 am
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Rick Willard
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Gordon...thanks so much for taking the time to share. I REALLY appreciate it. Unfortunately, I don't think this issue is the same as yours (was). I know that this string of messages is getting a bit long/ugly, but you'll see above I mentioned that the wallowing noise is following the RPM's/engine, and not the speed of the wheels, steering, load, overrun, etc. In fact, you can hear this noise when the engine is warm and the car is sitting still being revved a bit. So, for me, I think the mystery continues. Again, SINCEREST thanks for taking the time to share some insights!

Cheers!

Rick

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 Posted: 11-18-2014 04:45 pm
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Greg Fletcher
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A bad thrust bearing at the back of the crankshaft would allow too much lateral movement and possibly create some weird noise. I've seen a couple few of these deformed for reasons unknown on low mileage cars.

Rick, can you make a video and post it on youtube?

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 Posted: 11-18-2014 05:22 pm
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Rick Willard
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Now that is an interesting idea, Greg. Haven't even considered that before.... I will be glad to post a video as soon as I can. I'll need my rebuilt alternator back from you first to refit the fan belt.... :) Kidding...will get something out for review/consideration ASAP. Thanks again!!

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 Posted: 11-19-2014 05:26 pm
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Barthol
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Hi Rick,

This might be way off but it is an easy check.
During the Summer I experienced a similar intermitent noise coming from my Engine compartment.
I actually thought I had valve issues or worse.
Checking everything showed that my engine was OK.
What I finally found was that my Vacuum hose going to the Booster was collapsing under high Vacuum causing a gasping sound which from the drivers seat actually sounded as a mechanical error.

I just disconnected the hose and drove the car for a short trip ( be ware of very bad braking performance)
New hose on and everything sounded normal again.

BR
Kim

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