Loud rumble/growl when accelerating at low RPM

[90beater]

I have a 90 Ranger 2.3L 5spd, and when I accelerate at low RPM (1500rpm or so) in 3rd or 4th gear, the truck gets very loud. It sounds like vibration, and I see a little of that in the mirrors, but it doesn't really come through the wheel or the gearshift. The best way to describe it is like a growl or a rumble that seems to resonate through the truck. It happens under acceleration and, to a lesser degree, engine braking. Once the RPMs get above about 2k it goes away, also if you ease off the gas or clutch in.

I just bought the truck and put in a new (used) transmission and the exhaust seems to be good from the manifold/downpipe connection back. Noise was similar with the old transmission. Didn't replace the clutch since I was trying to keep costs down and it looked like it had plenty of friction disc left.

Anybody have any ideas what it might be or how to go about diagnosing it?

 

[Duane867]

U -joints, or it could be your cat heat shield,or the cat its self hitting the cross member.

 

[90beater]

I don't have a cat heat shield, and I know there was clearance all around the cat when I wired up the exhaust (which was later welded in by a good shop). I heard the rumble with the old exhaust before I cut it out, after I wired it in, and after it was welded in, so I'm guessing it's probably not that.

When I was replacing the trans, the u-joints all seemed tight with no noticable play in them. It's also the same 1500rpm noise in both 3rd and 4th gear, so seems like it's related to engine RPM and not roadspeed. No clunks, either, just that rumble.

I appreciate the input so far, any other ideas?

 

[scotts90ranger]

it's a 4 cylinder they vibrate a lot at low rpm high load, the 2.3 isn't happy there, you're lugging the engine and you'd be better off at a higher rpm in a lower gear

 

[90beater]

Interesting. I've never had another engine get that loud, or lug so high, but this is my first 4cyl truck. It's probably a little different from a Ford Aspire, huh?

What's the safest useful RPM range on this motor?

 

[RangerJack]

My first thought would be the heat shield on the catalytic converter. I have owned 4 rangers and even my current ranger..the heat shield breaks loose and then starts vibrating when you start to accelerate.

 

[90beater]

My first thought would be the heat shield on the catalytic converter. I have owned 4 rangers and even my current ranger..the heat shield breaks loose and then starts vibrating when you start to accelerate.

I've got a thin plate riveted to the body above the cat, and nothing below it but a crossmember. The plate riveted to the body is secure, and there's about 1" of clearance between the cat and the crossmember. Nothing on or near the cat will move if you pull/shake it.

 

[IRKillroy]

guys, how the fvck can a heat shield cause the mirrors to vibrate?? get your head out of your asses.

it sounds like an engine/tranny problem. It's called using the right gear for the speed. You have limited HP/Tq and you think that in a 1:1 ratio that engine is going to like the load you're putting on it? get real.

You've got guys giving you assistance for an operator error issue. go learn to drive.

Problem solved.

 

[90beater]

guys, how the fvck can a heat shield cause the mirrors to vibrate?? get your head out of your asses.

it sounds like an engine/tranny problem. It's called using the right gear for the speed. You have limited HP/Tq and you think that in a 1:1 ratio that engine is going to like the load you're putting on it? get real.

You've got guys giving you assistance for an operator error issue. go learn to drive.

Problem solved.

I don't know that it's that simple. 4th is 1:1, but 3rd isn't, and it'll do it in 3rd accelerating very gently on a fairly flat road. I don't expect it to make much power there, but I also don't expect it to get 10x louder than when it's spinning 500rpm faster. This is an empty regular cab short bed, so it's not that heavy.

I also drive a 4cyl 5spd Aspire, making 63hp peak, and I've had two other 4cyl 5spd cars. They're obviously not the same, but I've never seen anything like this with those, which is why I ask. If you're trying to drive at 600rpm, yeah, it'll lug. But I drove those between 1200 and 1800 rpm all day long, and as long as you weren't trying to go up hills, they all did fine.

If this motor has to spin over 2k to not lug, that's fine, but that doesn't seem normal to me, which is why I'm looking for input.

Edit: Keep in mind I'm not trying to be a race car driver, I'm driving like an old lady and trying to use the lowest RPM I can to not get left too far behind traffic.

 

[IRKillroy]

third is 1.5ish:1... still really crappy when you consider 2nd being about 2.2:1.

The power band of you engine is set to start around 2000 RPM up to 3800 RPM This is where your transmission will not have harmonic problems 'cause you engine isn't struggling to turn it.

those other whips of yours are as you said "not the same" and had different parts, engineers, manufacturing facilities... lets just stick to your wants and needs.

You want to drive it like your other cars 'cause you think it save fuel... what you need to do is drive it the way it was designed...

so I hope in this snarky reply you get your answer which you did not know how to ask in the OP.

 

[90beater]

I definitely appreciate the advice, even if it's snarky . Sounds like it's not indicative of a problem, so I'll just keep the revs higher and use the sound as a guide to keep it happy. Maybe a tune-up will get me a few lower RPM, and I'll check the compression while I'm in there.

Thanks to everybody who chimed in!

 

[scotts90ranger]

new spark plugs and wires wouldn't hurt, could be a misfire not helping anything.

I suggest Autolite 764 plugs gapped at .044", the drivers side takes a little patience to change, hardest part is getting the wires on and off of #3 and 4, you can stick the socket/extension through the break in the intake, on #4 either use a swivel or the proper mix of extensions (if I remember right an 8" and 3" was perfect).

the 2.3 is a tough engine, don't be afraid of revving it, it'll live fine spending all day at 6000rpm, keep in mind the torque peak is at around 2600 (best mileage), power peak is at 4600 (if you're pulling a hill and having issues holding speed, get it a little above that rpm and it'll do as good as it will)

 

[Duane867]

guys, how the fvck can a heat shield cause the mirrors to vibrate?? get your head out of your asses.

it sounds like an engine/tranny problem. It's called using the right gear for the speed. You have limited HP/Tq and you think that in a 1:1 ratio that engine is going to like the load you're putting on it? get real.

You've got guys giving you assistance for an operator error issue. go learn to drive.

Problem solved.

Hole in the cat could rumble at low rpm, vibrate mirrors, and shake the heat shield, or a leak in the exhaust just about any where combined with a bad hanger. Particularly at low rpm. Its called acustic pressure waves. Not to mention a bad hanger sagging the cat making contact a the heat shield with the cross member. Anything is possible with exhaust. We drive boxes on wheels bolted to steel frames. Thats how in the fvck it could cause it captain ass hat

 

[Ramirezsergio63]

he needs a more newer ranger

 

[Duane867]

and you need Rosetta stone LOL !