218 engine noise at higher rpm's

[WPVT]

The engine on my 1954 pickup has good compression and great oil pressure. It pulls well uphill at low rpm's, and idles very quietly and slowly. At anything above 40 mph, though, there's a clattering sound. I can't find anything obviously loose, and it has new front and rear engine mounts. The tappets haven't been adjusted during my ownership, but if they were the source of the sound I would expect to hear them at idle. 

Any thoughts or running tests I might try ?    

[JBNeal]

A loose timing chain could slap against the cover at high rpm...

[WPVT]

Thanks JB.

I just saw in an old post someone saying that a loose chain would only show on deceleration, not acceleration. The noise in mine shows up as the engine  reaches higher rpm's and continues steady all the while it is running at those higher rpm's. A slight back-off on the gas quiets it briefly.

Edited August 13, 2021 by WPVT

[kencombs]

2 hours ago, WPVT said:

Thanks JB.

I just saw in an old post someone saying that a loose chain would only show on deceleration, not acceleration. The noise in mine shows up as the engine  reaches higher rpm's and continues steady all the while it is running at those higher rpm's. A slight back-off on the gas quiets it briefly.

That sounds like an exhaust leak maybe.   does it do it when sitting still and brought to that rpm? That would be a very light load and lessened exhaust pressure/noise.   If it makes the noise when sitting still, I'd get a piece of heater hose, or some other tube to listen in suspect areas, like timing cover.

[Dodgeb4ya]

Rev it up in the driveway while looking and  listening under the hood....

If it's an engine noise you should hear it.

If you still cannot hear the noise from the engine area hack the rear end up and set on jackstands.

Put it in 1st,2nd and 3rd.

Rev the engine to the appropriate speedo range and try to locate the noise...go from there.

[WPVT]

Thanks. I'll try listening while the truck is stationary. I'm pretty sure it's not an exhaust leak as we planed the exhaust manifold last year. 

 

 

[Merle Coggins]

I'd be concerned that it is detonation at higher RPM under load. What is your ignition timing set to? 

[WPVT]

5 hours ago, Merle Coggins said:

I'd be concerned that it is detonation at higher RPM under load. What is your ignition timing set to? 

I couldn't tell you exactly where it is set, but a lot of thought and trial and error went into setting it. The engine will probably ping if I really load it, but that's not what I'm hearing. It's a mechanical clatter.

[JBNeal]

Weak valve springs might be causing valves and lifters to bounce around on the cam at high rpm...

[WPVT]

I just drove the truck into town to my garage/shop. At 45 mph I started to hear the clattering sound, but only if I was applying gas. If I backed off at all, it stopped. Having said that, it really isn't coming from the engine being under load particularly, it's from the higher rpm's.

 

With the truck stationary and the hoods up, there is no clatter at higher rpms. Could it be something associated with the clutch ? I know that it isn't the starter gear drive on the flywheel, so I can eliminate that possibility. The fuel pump was rebuilt recently and has a new spring. The truck doesn't make the sound going up hill in a high gear, like an engine being lugged.

 

I'd like to try running without a fan belt, but it's in the 90's today so that's out of the question. 

 

I'm sure many mechanics wouldn't find it abnormal for a 70 year old truck engine to make sounds at higher rpm's, but this is a straight six in good shape and it should hum, in my opinion. 

Edited August 13, 2021 by WPVT

[wagoneer]

to summarize

 

——

a) high rpm + accelerator = noise

b) highish rpms and no accelerator != noise

c) noise is definitely coming from engine bay

d) clattering  noise like metal on metal clashing

 

 

Key component is acceleration (wide open throttle). When let off throttle, noise abates.

this tells me the engine is not the issue because it is spinning at high rpms doing its thing with and without the noise. This leaves carburetor
 

 

 

Couple things:

1. take a short 15 second video of the Noise occurring and abating and then occurring again when you accelerate.

 

 

2. Clattering noise might be from an accessory, carb linkage, throttle cable, wire, chain or something connected to the engine and vibrating heavily (and loudly) under the combination of high rpm.

 

3. Check the carb for loose or wet areas at the gaskets.

 

I have a whine noise that I can hear through my carburetor that I suspect to be a vacuum leak. a rebuild is part of its future.

 

 

Really the info you provide does limit and refine areas to investigate as you have said:
.

 

1)Start with your carburetor . Consider vacuum leaks even possibly your vacuum a advance. 
 

2) maybe engine mount bolt loose allowing engine to move ever so slightly during load 

Edited August 13, 2021 by wagoneer

[WPVT]

3 hours ago, wagoneer said:

to summarize

 

——

a) high rpm + accelerator = noise

b) highish rpms and no accelerator != noise

c) noise is definitely coming from engine bay

d) clattering  noise like metal on metal clashing

 

 

Key component is acceleration (wide open throttle). When let off throttle, noise abates.

this tells me the engine is not the issue because it is spinning at high rpms doing its thing with and without the noise. This leaves carburetor
 

 

 

Couple things:

1. take a short 15 second video of the Noise occurring and abating and then occurring again when you accelerate.

 

 

2. Clattering noise might be from an accessory, carb linkage, throttle cable, wire, chain or something connected to the engine and vibrating heavily (and loudly) under the combination of high rpm.

 

3. Check the carb for loose or wet areas at the gaskets.

 

I have a whine noise that I can hear through my carburetor that I suspect to be a vacuum leak. a rebuild is part of its future.

 

 

Really the info you provide does limit and refine areas to investigate as you have said:
.

 

1)Start with your carburetor . Consider vacuum leaks even possibly your vacuum a advance. 
 

2) maybe engine mount bolt loose allowing engine to move ever so slightly during load 

Thanks for your thoughts, and trying to bring logic to the process. I'll take it out on a morning without traffic and pay around with the noise. I like your idea of a loose mechanical linkage, especially because it would be a cheap fix. I think vacuum issues can be eliminated as I have a steady 19 on the gauge. Motor mounts are also new and correctly tightened. 

It could be just a rattle I suppose, but it's such that I don't feel comfortable pushing the engine up to 50 mph. 45 mph seems like a more comfortable maximum rpm. Now that I think about it, I think it has to be engine related because the noise limits how far I want to push the engine. I don't know my rear end ratio, but I do know that low gear isn't very low, so high gear must be reasonably high.

Is 50 or 55 mph a reasonable cruising speed for these trucks ?  

[wagoneer]

HI @WPVT

  Others on the forum have said that their trucks max out at 45/50 mph due to the low rear end ratio. It could be also you are approaching  redline , so things are really shaking then, and maybe something slightly worn/loose is echoing through. My B2B is 4.1 differential ratio, and with stock wheels, we have a bit of an issue.Redline is 4000, so in final 1:1 drive, the max is shaking at 45 mph. You could increase your tire size for a modest improvement in top end.

 

 

 

 

[Merle Coggins]

2 hours ago, wagoneer said:

HI @WPVT

  Others on the forum have said that their trucks max out at 45/50 mph due to the low rear end ratio. It could be also you are approaching  redline , so things are really shaking then, and maybe something slightly worn/loose is echoing through. My B2B is 4.1 differential ratio, and with stock wheels, we have a bit of an issue.Redline is 4000, so in final 1:1 drive, the max is shaking at 45 mph. You could increase your tire size for a modest improvement in top end.

 

 

 

 

 

@wagoneer, 

There’s a flaw in your calculations… Your need to use total tire hight/diameter, not rim size. The best way to find that dimension it is to measure from the ground to the center of the axle and double it. You’ll likely find that your number will be closer to 28-30 inches. 

 

Also, I wouldn’t want to spin a flathead up to 4000 RPM. I don’t like pushing mine past 3500. Where did you find the 4000 RPM  redline number? I’ve never seen a published spec for that. 

Edited August 15, 2021 by Merle Coggins

[greg g]

My coupe has a 4.11 rear end.  My calculator showed 3280 rpm equalled 62 mph with 225 75 15 (27.75 inch diameter tires)  speedo registered 65 while comp speed on GPS was 62. When I asked the guy who did the machine work for my rebuild about safe cruising rpm, he said that he always went with the 85% rule.  That is peak HP rpm times .85 for our engines factory peak HP rpm is 3600.  Which works out to apx 3100 rpm for sustained operation.  This assumes proper oil quantity and pressure, and operation in normal coolant temp range.  Which means for most of us with 3.89 to 4.11 rearends, 55 mph is sustainable road speed, with 60 to 65 available if needed.

 

There are some calculators which give you a piston speed equivalent and a do not exceed speed based on stroke length.  For long stroke engines this usually shows the longer the stroke, the shorter the piston speed limit.

Edited August 15, 2021 by greg g

[WPVT]

Thanks to all. I haven't verified the rear end ratio. I do know that the lowest gear isn't terribly low (3 speed) , so I expect that I have the stock ratio rear end, somewhere around 3.7 as I recall. I don't expect to run the engine at 4000 rpm, or even 3500 on a regular basis. I'm happy at 40 mph, but not the other guys on the road. So I'd like to be able to loaf along at 45 or 50. With the low end torque this engine has, it's a shame there isn't overdrive. 

 

I spent some time with the truck yesterday. Sitting still, the the engine can be brought up to higher rev's with no ill effects or unusual noises. My noise and vibration problem at 45 mph while driving, certainly sounds like it's coming from the engine, though, or maybe up front in the drive line. I know it isn't alignment, tires, etc. 

 

Maybe I need to hook up a tach I can read while driving, just so I'll know what the rpm's are. 

 

 

[ggdad1951]

My 1 ton with 4.1 goes 55 to 60(ish) all day long running at 2800 RPM (via tach), but I got me some tall tires.

[WPVT]

48 minutes ago, ggdad1951 said:

My 1 ton with 4.1 goes 55 to 60(ish) all day long running at 2800 RPM (via tach), but I got me some tall tires.

Thanks. That's good to hear. So 2800 is maintainable without pushing things.

[ggdad1951]

it's as high as I like to go, I believe 3200 is where the danger really starts.

[WPVT]

1 hour ago, ggdad1951 said:

it's as high as I like to go, I believe 3200 is where the danger really starts.

It's time for me to figure out just what my RPM's are, so I know what to expect. 

[Jeff Balazs]

Sure sounds like detonation to me. It is easy enough to make a few small timing adjustments to see if that has any effect. This is where I would start.

Jeff

[WPVT]

3 hours ago, Jeff Balazs said:

Sure sounds like detonation to me. It is easy enough to make a few small timing adjustments to see if that has any effect. This is where I would start.

Jeff

Just to be clear, is this the ping that you hear if you overload an engine at low speed, i.e., trying to go uphill in too high a gear ?  

[Merle Coggins]

5 hours ago, WPVT said:

Thanks. That's good to hear. So 2800 is maintainable without pushing things.

 

I've done a few trips with my truck where I ran a sustained 3000-3500 RPM for several hours without issue. But I also know the condition of my engine as I built it. 

 

3 hours ago, Jeff Balazs said:

Sure sounds like detonation to me. It is easy enough to make a few small timing adjustments to see if that has any effect. This is where I would start.

Jeff

 

I agree with Jeff. A few years ago I started experiencing detonation "ping" at higher RPM under load. It did have a bit of a "clatter" sound. I kept telling myself, "One of these days I'll get around to investigating it". Eventually it knocked the electrode center out of a couple of spark plugs causing a serious loss of power. I found that I had a bad vacuum advance causing a vacuum leak, which likely leaned out my air/fuel mixture leading to the 'pinging'. After replacing the vacuum advance and spark plugs, and adjusting the valves, all runs good again. In hind sight it could have been much worse than a couple of failed spark plugs. You can damage pistons, wrist pin bushings, and/or con rod bearings due to continued operation with serious detonation. 

[Los_Control]

19 hours ago, WPVT said:

Maybe I need to hook up a tach I can read while driving, just so I'll know what the rpm's are.

I would be concerned myself with no tach .... if I could actually drive my truck  ?

Going to give a shout out to @Tubman This is the way I am going to go. Basically you can use any modern 12 volt tach, or score a cool old school tach on ebay and convert it to 6 volt positive ground. To be clear, you provide the tach, @tubman provides the electronics to run it. And for a price I think is reasonable.

Considering a 6volt positive ground tach is almost unobtainable.

https://www.jalopyjournal.com/forum/threads/tach-set-up-for-crab-distrubutor.1173851/#post-13350521

 

[WPVT]

Thanks. As to a tachometer, I have one,but I'll have to rig it so I can drive and watch it.

I'm pretty familiar with engine ping and what it sounds like. That's not what I am hearing.