Alfa Romeo Forums banner

1 - 13 of 13 Posts

·
Premium Member
Joined
·
488 Posts
Discussion Starter #1
I found this searching the forums.

It is true that today's four cylinder engines are very happy,buzzy little affairs. The engines in our Alfas are just form a different era and they are not as smooth and have something of a grunt to them when pushed hard. I am not talking about the note from the tailpipe but the engine sound you get through the firewall. That said I am going to take this conversation in a slightly different direction. Maybe your engine is fine but you have a bit of vibration thing going on at higher RPMs that is making things seem rough. The first Alfa I ever drove was on a test drive. I said to the owner, the engine did not seem happy, like it didn't want to go. It seemed to get rough and loud almost defiant when pushed. He disagreed (surprised). After a little while I said, maybe it is just the muffler and wouldn't you know it the muffler fell off shortly there after. I did not buy the car. Maybe you are getting vibrations from a failing exhaust system or you need new motor mounts. Motor mounts are new, are all the bolts that hold the air plenum from underneath there and secure? Maybe it is really the drive train that is resisting. If you have not driven the car recently with the top up you should, you get a much better audio feedback from he engine and transmission with out all the wind noise. My guess is that you have a problem but it is not an engine problem (good news).
the engine did not seem happy, like it didn't want to go. It seemed to get rough and loud almost defiant when pushed

Mine is doing the same thing. Here is what I have done (me or shop).

New motor mounts (2 months ago)
New intake runners (2 months)
New transmission mount (1 year)
Rebuilt driveshaft kit from CenterLine (1 year)
All new vacuum hoses, cleaned OVS
Shoe glue main air intake hose
New O2 sensor
New muffler (1 year)
New shocks (6 months)
Some rear suspension work, new bushings (4 months)

It now idles better than it ever has. Can rev up to 5k in driveway. Shifts better than ever. Even drove it in 26 degree weather.

But when driving, it gets loud and it doesn't want to really go. Car has lots of overall vibrations. Driving it wears me out after a while.

Thoughts:
1. Still has original center muffler. It might have a hole somewhere or just worn out. Would that cause the car to be down on power? (Getting one soon.)

2. Injectors need cleaning? (Need to do that anyway.)

3. Does something in the drive train needs realigning or balancing? I get a grumble sometimes when letting off the gas at times. But no clunks.

4. Still has original front suspension parts that I know of. Could it be causing some of the overall vibrations?

If I push in the clutch when doing down a hill, it coasts relatively smoothly.

The suggestions will tell me if it's something I can troubleshoot/fix or I need to take it in somewhere. Sorry for the long post.
 

·
Administrator
Joined
·
17,055 Posts
...when driving, it gets loud and it doesn't want to really go. Car has lots of overall vibrations. Driving it wears me out after a while.
Do you have a catalytic converter? They can get plugged up which restricts exhaust flow. Which means the engine can't 'go' although it may idle fine and rev up with no load.

Does something in the drive train needs realigning or balancing? I get a grumble sometimes when letting off the gas at times.
Giubo's in good shape? U-joints in phase?

Tires reasonably fresh & balanced? Old tires can take on a set - become flat spotted - from sitting for a long time. Sometimes that will go away after a long drive as the tires warm up but often it'll become permanent.
 

·
Premium Member
Joined
·
488 Posts
Discussion Starter #3
Do you have a catalytic converter?
Yes. Is that something I can test? It has the original catalytic converter and center muffler at 130k miles. I have that nagging feeling it is bad.

Giubo's in good shape? U-joints in phase?
Will look at the Giubos. Not sure about "U-joints in phase". What does that mean exactly? I had the driveshaft parts replaced by someone else.
 

·
Administrator
Joined
·
17,055 Posts
Often a plugged catalytic converter will get very hot. Normal is ~ 350-400F at the inlet side and ~ 100F higher on the oulet side. A non-contact thermometer can be used to check temps. Or, if it glowing red after a long drive it is likely overheated.

The U-joints have to be in line with each other. There is a splined section (between #25 #26) to allow the driveshaft length to vary slightly as the rear axle moves up & down. If the splined section is not assembled with the U-joints aligned the drive shaft is out of phase. This will cause it to bind & release as it turns.
 

Attachments

·
Registered
Joined
·
2,156 Posts
Get other opinions before doing anything based on this, but isn't it also possible the drive shaft itself is out of balance?
 

·
Premium Member
Joined
·
488 Posts
Discussion Starter #7
To me its road-speed related since it's smooth when idling. But not worse at 60 vs 30 mph.

Just got back from the exhaust shop. He said I was doing pretty good. No leaks. Everything seemed tight. The end muffler is a year old. Got good output pressure. The center muffler had been replaced but is not factory. A bit rusty but said I could go 2-3 years more. Converter looked real good. Again, new O2 sensor. Wasn't to hot. Headers had some place welded but no leaks. Gave me a OK overall. That is good since that is one thing I can check off.

Also pointed out newish front suspension parts I hadn't noticed. That is also good.

I am going to get the injectors cleaned. That might help overall engine running. And take it somewhere to check the overall drive shaft area is ok. Perhaps something is out of alignment or needs balancing. I can't do that myself.

I think I have a plan to at least go forward. Thanks for all the suggestions.
 

·
Premium Member
Joined
·
21,713 Posts
If you rev the engine at rest, does it make the vibration?
If you put the trans in neutral at speed, does the vibration persist?

Andrew
 

·
Premium Member
Joined
·
488 Posts
Discussion Starter #9
If you rev the engine at rest, does it make the vibration?
Seems to rev ok in driveway. Nothing out of the normal for these engines that I know of. I need to drive some other spiders to see how they run to compare.

If you put the trans in neutral at speed, does the vibration persist?
I haven't tried that exactly. Clutch in doesn't make the vibration. Coasts ok. I will check that specifically.
 

·
Premium Member
Joined
·
21,713 Posts
Or at a speed where it makes the vibration, shift into a different gear but keep the same roadspeed. Vibration persist? Trying to determine if it's engine-speed related or drivetrain-speed related, which are not the same thing. Implicate different components.

Andrew
 

·
Registered
Joined
·
17 Posts
Have you checked the oil pan guard? Sometimes even if you replace the engine mounts (It happened to me) the engine touches the oil pan at high revs, and you will get vibrations at any speed, it will depend mostly how much you rev your car.
 

·
Premium Member
Joined
·
488 Posts
Discussion Starter #13
Just wanted to give an update on this thread.

1. I replaced the center muffler. Much quieter overall. The guy who did it had it up on a lift. Showed me where I had newish front suspension parts. That make me feel better.

2. I had the fuel injectors cleaned.

But still had the vibration and noise issue.

It ended up being the bushings for the AC compressor. I first just cut the belt. That fixed about 85% of the issue. This weekend I removed the compressor and bracket. The AC wasn't working anyway.

Way better! Before, anything after 70 mph was to loud and vibrating. Now I can get to 75. I would like to get the car to 80 and run smooth. I am going to get the tires rotated and balanced next just in case.
 
1 - 13 of 13 Posts
Top