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Discussion Starter #1
I was driving my brother's 87 2.5 Milano today and it started making a knocking sound and then proceeded to lose power and barely idle. I finally had it towed home after that. The car hasn't been run in 20 years due to timing belt breaking and bent valves. I replaced the heads a couple of years ago and then had fuel supply issues. We finally got it running and it was running very nicely although it always had a bit of clatter from the engine. I thought it was the lifters as it wasn't that bad. Today it first seemed to have slight fuel injection problems at partial throttle but then with an application of full throttle and some revs, it would appear to go away and return to full power. But then the clatter turned into knocking and roughness until I didn't want to risk any further damage and I shut it off. I did open the hood and listen closer to the engine and it seemed like the noise was coming from the heads but it was hard to tell so not sure if that tells us anything.

Any ideas? I've never heard of rod knock in a V6 but I'm sure it's possible. Any other possible explanations or tests I can do? Or is there a similar sounding valvetrain issue with these cars? I hate to think the engine has to come out or even that the heads have to come off as I'm only here twice a year for limited time.

Thanks for any help.
 

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Richard Jemison
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Pull the cam cover off the noisy side. Look for a bent push rod or bent rocker. The "blade" type rockers will bend (or break) If a rocker is bent it will not be centered exactly over the valve tip. Head has to come off to replace one.
Lash settings are critical on the exhaust side. Shouldn`t be less than .007 at the cam follower.

Check cam timing again as well!
 

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Discussion Starter #3
Pull the cam cover off the noisy side. Look for a bent push rod or bent rocker. The "blade" type rockers will bend (or break) If a rocker is bent it will not be centered exactly over the valve tip. Head has to come off to replace one.
Lash settings are critical on the exhaust side. Shouldn`t be less than .007 at the cam follower.

Check cam timing again as well!

Thanks so much for the help and hope that the engine might not be gone but I honestly can't tell where the noise is coming from. Even with a stethoscope but loudest knock seems to be at the oil pan. I can't really get the stethoscope on the block anywhere. Without the stethoscope, the noise is most apparent when standing in front of the engine and doesn't appear to be coming from a specific side; in fact it is more difficult to hear when listening from either side of engine (over the fender.)

The noise was present at idle when first starting from cold but once it warmed up, it's barely audible at idle and comes on with revs.

Listen to the video and see if that can tell us anything, sorry for the slipping alt belt and wait for the revs to truly hear the knocking. It's most noticeable towards the end of video.

 

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Premium Member
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On these engines when a rod knocks it's almost always the #1 rod (which has the weakest oil supply). Drain the oil and remove the lower pan. You can reach up and grab the #1 rod. If you can rattle the rod against the rod journal, well then there's your knock.
Also when you're draining the oil, drain it into a clean bucket. As the oil drains shine a flashlight at the stream. If you see silver flashes in the oil stream, that bearing material, not a good sign.
Examine the inside of the lower pan with your flashlight. Lots of shiny material in the lower pan ? again not a good sign.

Now there's always going to be some junk material in the bottom of the oil pan. Collecting that junk, is part of the oil pan purpose, with experience you can get to be a judge of what is too much, and what's okay.

Hope this helped.
 

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Just take the valve covers off. If it's all good under the valve covers, then your problem is the bottom end.
 

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Discussion Starter #7
Video sound indicates a rod bearing or broken piston.
Thanks. I thought so. Arghhhh!

Thanks so much for the help! I'll have to postpone any further work on this car until summer as I'm back to my healthy and well running Milano (knock on wood) in LA tonight. And my newly acquired S cams which will transform my 2.5 into a high revving race car, right? Yeah, I know.

Richard, how much is a set of cams that would pass smog (I've found that even pretty crazy cams pass smog but maybe I've been lucky) and still keep pulling at higher revs? What do you offer and what kind of range of $? Curious for future modifications.

Thanks to all regarding this knocking car; more to come at a later date....
 

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Discussion Starter #9
Send me an email to [email protected] and I`ll send you a PDF file of lobe designs and a proper pairing that will make much better power and torque and still pass emission testing.

Think about changing to a 3 liter!

Rj
Email sent.

Yes, a 3 liter would be nice, I think. I've never actually driven a 3 liter before and I'm a little sad about the lower rev limit but I can't argue with 30 more hp. I don't really have a space to do engine exchange anymore so a bigger engine will need to wait. Plus, my poor Milano is beat up and not pretty from years of LA parking abuse so all that work might not make sense. Hmmm, sounds like I need another Alfa! I wish I could have grabbed that entire 164S engine from the junkyard instead of just the cams but couldn't do it at this time.

Thanks again....
 

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Raising the rev limit on a 3L L-Jet cpu is simple but the 3L motor is all about torque
 
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