Alfa Romeo Forums banner

1 - 20 of 36 Posts

·
Registered
Joined
·
30 Posts
Discussion Starter #1
Hey people. Just got my Milano Verde a month of so ago and the other day I was playing in a parking lot. Leaving the lot I started to hear a knocking and ticking from the bottom end. I checked the oil and it was just below minimum... I topped it off and still the noise is present, louder when warm and when under load. In my experience that's crankshaft bearings right? Anyways, I've never pulled an engine from a car and I'm not sure I want to sink a ton of money into this car so I figured I'd ask...

Should I swap in a used 3.0l? How often do these come up? Is the 164 motor viable?

Should I pull it and rebuild the bottom end (provided I prove that to be the problem)? What are the costs associated with that?

Any tricks I should know about diagnosing the problem without having to pull the motor out?

Currently I'm going to change the oil and add some Bardahls to see if it helps at all. Any help is appreciated.
 

·
Premium Member
Joined
·
13,991 Posts
Used 2.5L motors have little value. You should be able to pick one up for a few hundred dollars if your motor is bad. Where are you located?
 

·
Registered
Joined
·
659 Posts
Just below minimum isn't good to run at, but there is margin built in and depending on how much sloshing occurred from corning, that might not neccessarily be the source of your problem.

There are a few parts that could cause knocking. I would definitely park the car until you can better diagnose.

A quick check that helped me once is understand the frequency of the knock. Say idle is 600 RPM; the crank would turn over 10 times per second and the cams should rotate 5 times per second.

If you find that the frequency is at cam speed, use a screwdriver against the valve cover to determine which cylinder is the source. Then, compression test, pull valve cover, etc.

If it's at crank speed, it might be rod knock. I'd drain the oil to check for bearing debris. A spun bearing will probably have left some bearing and crank debris, but it might not be so obvious.

After that, I'm not sure what I'd recommend. Personally, I would pull the engine and flip it over to check the bearings.

Bearings are relatively cheap (figure on $200 for cranks+mains), but if you've damaged the crank, your oil passages will be full of contamination, so your safest bet would be to clean out block/head and inspect the oil pump. The cleaning shouldn't be more than $200 at a machine shop. I don't think anyone here likes to repair the nitrided cranks, so it would be best to source a used one from Alfa Parts Exchange or similar. Figure on $150 for a crank.

After that, it depends on how thorough you want to be; every part has pretty exacting dimensions and specs that would ideally be checked, but you can do a risk assessment.

I sent you a facebook request in case you have questions.
 

·
Registered
Joined
·
30 Posts
Discussion Starter #4
So I just changed the oil and added a Bardhals thickening stuff. No debris present and no real change to the symptoms.

Thanks for the tip about diagnosing. I will look into that shortly. Good to know that the bottom end won't cost me a boat load!
 

·
Premium Member
Joined
·
844 Posts
How to check connecting rod bearings

Hi

When Alfa V6 motors begin to knock it's almost always the #4 connecting rod, followed by the #1 connecting rod. You can visually inspect and place your hand on these two connecting rods by removing the lower oil sump cover.

One of the nifty features of the Alfa V6 motor is that the bottom of the oil sump is removable. Order up a few lower sump gaskets, drain the oil, and remove the lower sump.

Examine the sump surface. If you find metal fragments that's a bad sign. Now reach up and grab the bottom end of the first connecting rod (which is #4) and see if you can move it from side to side, it should only move a tiny bit. If it moves enough to make a knocking sound, then it's definitely toast.

Grab the second connecting rod (piston #1) and try to move it from side to side. In a good engine both the #1 and the #4 connecting rods should have the same amount of side to side motion, and that motion should be minimal.

In any event it's not the end of the world. Get yourself a good used 164 motor and turn it into a Verde engine by using your Verde engine parts, or buy a 164 crankshaft and use it to rebuild your existing motor. In either case you'll need to fabricate a spacer between the 164 crank and the Verde flywheel.

Hope this helps
 

·
Registered
Joined
·
30 Posts
Discussion Starter #6
So I think I was overreacting and speaking to some people with vastly more experience than me, it sounds like I'm just pinging...

This lead me to look into timing it correctly and I noticed lots of slack in the timing belt. I printed the template out which allows me to check cam timing and as I turned the cams to line it all up the belt slipped. So, I am for sure not timed correctly now. I examined the tensioner and from what I can see, this is the dreaded mechanical unit, correct?



If this is the mechanical unit, I'd like to go back to the hydraulic unit (as it seems everyone advises). I want to do this step first, then reassemble and time the engine correctly before I go further. Can anyone help me with that?
 

·
Registered
Joined
·
30 Posts
Discussion Starter #7 (Edited)
I guess I'm answering my own questions here but I've always been one who thinks out loud. My tensioner looks exactly like this one which appears to be the mechanical unit. Alfa Romeo Milano GTV6 164 V6 Timing Belt Tensioner | eBay

So, how do I go about converting back to hydraulic (if that's my best option)? Are the tensioners for the 2.5, 3.0 and 164 3.0 motors cross compatible?
 

·
Registered
Joined
·
8,782 Posts
1 st you need to locate a hydraulic tensioner. They are not easy to come by, and you need to make sure you have all the bits and pieces that go with it...backing plate, springs, stud, etc. Then you need to buy the rebuild kit and rebuild the hydraulic tensioner. Once you get all that together, you simply remove the mechanical tensioner, remove the stud for it, and remove the allen screw that was likely used to seal off the oil hole. Make sure everything is good and flat before installing the hydraulic tensioner or you'll get a leak.
 

·
Premium Member
Joined
·
13,991 Posts
Another alternative is the "Zat" fixed tensioner. The pro's are they don't leak and they don't fail. The con is the belt has to be adjusted every 15k miles. I think that Centerline may have a few in stock. I will only use that type of tensioner.
 

·
Registered
Joined
·
8,782 Posts
I run modified hydraulic tensions on both my 164Ss. They don't leak either, don't use oil and the belt doesn't jump. I prefer them over the Zat tensioner because it's easier to set the correct tension on the belt, but again it has to be adjusted every 15,000 miles or so. I'm not a fan of mechanical tensioner because I had a belt jump years ago with one. I've probably got over 200,000 miles on my modified hydraulic tensioners. Other people have had great success with the mechanical ones. I just got scared off.
 

·
Registered
Joined
·
3,890 Posts
I dislike[strongly] mech tensioners.
I prefer a good hyd tensioner run dry, leave the oil block off allen screw in.
With a good bearing, you are good to go.
 

·
But Mad North-Northwest
Joined
·
10,492 Posts
Okay, compadres. Perhaps before y'all launch into YET ANOTHER tensioner discussion (of which there are about a million if you search) perhaps it would be a good idea to work the problem at hand first.

This lead me to look into timing it correctly and I noticed lots of slack in the timing belt. I printed the template out which allows me to check cam timing and as I turned the cams to line it all up the belt slipped. So, I am for sure not timed correctly now. I examined the tensioner and from what I can see, this is the dreaded mechanical unit, correct?
The mech tensioner usually works fine if set up properly. Anyway, if your belt was actually loose you need to sort out what issues you have before just replacing the tensioner. If the belt slipped and you had mechanical noises it's entirely possible you were hearing the pistons kissing the valves. It's also entirely possible that everything was fine, the mechanical noise was something else, and you just screwed up the tensioner & timing when you tried to turn the cams.

You said it slipped when you turned the cams. Were you turning the crank pulley or trying to turn at the cams? Did you turn the crank pulley forwards or backwards? If you did anything besides turn ONLY the crank pulley ONLY forwards then "you done screwed up bad, son", as the saying goes.

Your tensioner indicator is way the hell off, but that could be from you turning things backwards (if that's what you did). You need to VERY CAREFULLY get things back in time, then see if your tensioner is busted. Then you need to figure out the condition of your valves vis-a-vis piston contact. Unfortunately the trail of exactly what happened may be cloudy at this point.

If you're not intimately familiar with timing a V6 and changing the belt & tensioner, this is probably not the best situation to learn in. In that case I strongly suggest finding a competent Alfa mechanic: things can get real expensive real quick if you don't know what you're doing.
 

·
Premium Member
Joined
·
844 Posts
Hi MS Smith

First of all post your location. Where you and your car reside, determines what kind of help and resources you can access.

Second do not start or drive this car until you have a better handle of where the valves are in regarding to the pistons. You can bend valves at idle as easily as you can at high rpm.

Get yourself a big socket ( search this site for the size) and a big socket driver and use that to turn the motor over when you are investigating the timing. Some people push the car in 4th gear to turn the motor over. I think this is a risky procedure. The car weights over 2,500 lbs. When it is moving even super slowly it has a enough force to bend an errant valve.

All the best
 

·
Registered
Joined
·
8,782 Posts
Yes, check the timing. Rotate the engine manually to as close to timing marks as you cam. Using the template, reset the timing, then check the compression. If you have bent valves they will show up.
 

·
Registered
Joined
·
30 Posts
Discussion Starter #15
This was my process:

I was driving the car when I heard what was described as pinging. This noise happens only under load and there is no loss of power. I got the car in the garage, the timing belt looked loose and so I set about checking the timing. I turned the passenger side cam clockwise with a socket (I know I should have turned the crank pulley but I don't have the appropriate socket for it). At this time I saw it slip and slowly began turning the drivers side cam carefully feeling for piston to valve contact. Everything felt ok but clearly the timing was now off so I pulled the belt off to inspect the tensioner. Currently the car is sitting with the belt off while I sort out how to proceed with the tensioner.

Now I want to make sure my tensioner is working correctly, which I read up on. After I verify it is not broken I plan to put it back together correctly to see if I continue to hear the noise, at which point I would suspect bent valves.

If I do in fact have bent valves, I have done some reading on the various tensioners and if possible will use a hydraulic tensioner.

I have done a timing chain on the M10 motor in my BMW 2002 which was farily easy so I have confidence that I can do this job, I'm just worried that this mechanical tensioner won't cut it. I plan on tracking the car some too.

Does that sound like a solid plan?

Anyways, I appreciate everyone's help with this. You guys are much more detailed and specific and scientific than the BMW community haha.
 

·
But Mad North-Northwest
Joined
·
10,492 Posts
I was driving the car when I heard what was described as pinging. This noise happens only under load and there is no loss of power. I got the car in the garage, the timing belt looked loose and so I set about checking the timing. I turned the passenger side cam clockwise with a socket (I know I should have turned the crank pulley but I don't have the appropriate socket for it). At this time I saw it slip and slowly began turning the drivers side cam carefully feeling for piston to valve contact.
Okay, yeah: you done screwed up bad, son. If you tried to turn at the cams, they will slip no matter how good your tensioner is. Good news is that if you don't screw up more your valves are probably fine for now.

I'm not trying to be hard on you here, but you're kind of in a cascading failure mode right now: turning the passenger cam was bad, and then after it slipped following that up with turning driver side cam was even worse. So before you do anything else PLEASE ask questions or things can get REALLY expensive.

Also, don't get too caught up in the tensioner debate. There are a ton of opinions on tensioners and all the opinions suck in one way or another. Many of us have run the mechanical tensioners for a long time with no issues.

Your first step is that you're gonna need to get the cams and crank back in time somehow...
 

·
Registered
Joined
·
30 Posts
Discussion Starter #18
Whoops! Well you have to learn somehow. I will look into how to time the cams relative to the crank now.
 

·
Premium Member
Joined
·
13,991 Posts
You may escape without damaging anything if you did not run the engine with the displaced timing. I know of a couple of instances where the belt jumped and the engine ran briefly with no serious damage. Time the motor correctly then do a compression check. If the compression is good on all cylinders then you are in luck. You will have to pull a head if any of them are near zero.

The tensioners that rely on springs require you to not turn the engine backwards. There is no such restriction with fixed tensioners.
 

·
Registered
Joined
·
8,782 Posts
Steve has a post on the 164 form on how to rotate cams and crank with the belt off to get the timing marks lined back up.
 
1 - 20 of 36 Posts
Top