'87 325 rod knock or need valve adjust

[Jon K]

My mom bought an '87 325 in great shape. Had the timing belt done, etc. It has like 245k ish miles. Seems fine though. However last night I was replacing her head light bulb and noticed a very slight tap/knock. It was very loud at all, and could just barely be heard over the car running though it took me a few minutes to get my mom to even hear it while running. I don't know when the last time the valves were adjusted - we've owned the car for prob... 5 months or so. So should I start worrying about rod knock on the 2.7 eta or am I hearing a noisy rocker or something? Is there a good way to determine what's going on? These SOHC cars are new to me.

I should say that the car drives fine it seems and you can't hear this noise from in the car. At anything over idle outside of the car hood up, its hard to hear if at all audible.

Thanks guys

[Blitzkrieg Bob]

Wecolme to the M20.

The valves are mechanical and may need to be adjusted...a two beer job at the most.

just need a new cover gasket and be careful with the vent hose and all should go smooth, if you have a remote starter that is a time saver too.

I just bump the starter and go down the line twice.


if it doesn't quiet down it may be a worn eccentric that has a flat spot.

[Blitzkrieg Bob]

Thanks Bob I will admit I am not a big SOHC fan for this reason. Though, does this noise sound like it could be a noisy valve train? I'd hate for the car to have rod knock or something as thats a bit more serious (and expensive). The car is immaculate and worth keeping, so I'd need to find another engine if that were the case. Do you think out of whack valves could sound like a medium toned tapping/light knocking?


Adjust the valves first and see how it goes.

change the oil and filter 15w50

Bottom end noises are more deep knock and tend to go away under certain speeds and load.

A stethoscope would help ease your mind

[Jon K]

Thanks Bob I will admit I am not a big SOHC fan for this reason. Though, does this noise sound like it could be a noisy valve train? I'd hate for the car to have rod knock or something as thats a bit more serious (and expensive). The car is immaculate and worth keeping, so I'd need to find another engine if that were the case. Do you think out of whack valves could sound like a medium toned tapping/light knocking?

[whiskychaser]

rod knock on the 2.7 eta
I dont know what this is. But you would know if its a big end from the 'thump' and speed so I can only assume its the small end you mean. There is the possibility of piston slap or the cam has worn through the hard surface. UK Fords used to suffer from that but that was probably before you were born:)
Not a great deal you can do about either without ripping it apart bt an engine stethoscope may help narrow it down (cf ferret.. hosepipe, barney..screwdriver)

[Macv]

+1 to the normal m20 ticking. My 3 (as most) does it as well.

[winfred]

sometimes the valves can rap pretty hard and the noise is magnified by all of the aluminum, m20 bottom end problems are very rare and when they **** up it's usually exciting with lotsa holes, by far my favorite m20/30 oil is chevron delo 15w40 conventional, it's miracle sauce for the solid lift valve train, old ass wornout motors and fresh all new parts rebuilds all of them have quieted down a amazing amount, i like doing the adjustments with the engine as hot as i can stand at factory spec

[Jon K]

sometimes the valves can rap pretty hard and the noise is magnified by all of the aluminum, m20 bottom end problems are very rare and when they **** up it's usually exciting with lotsa holes, by far my favorite m20/30 oil is chevron delo 15w40 conventional, it's miracle sauce for the solid lift valve train, old ass wornout motors and fresh all new parts rebuilds all of them have quieted down a amazing amount, i like doing the adjustments with the engine as hot as i can stand at factory spec

So you feel pretty confident that its not bottom end noise? I want to adjust the valves but I am not sure i'll get a chance this week. Hot for sure? No cold Winfred? Hrm.

[Bin_jammin]

Hot. Parts will expand when heated, if you adjust when hot they'll be at their max expansion. If you adjust valves when the engine is cold, they could be too tight when hot.


Nobody ever thinks it's a wrist pin, I've seen them make tons of noise that's usually a good "fool-you" noise. Sounds like it's coming from too high to be a bearing, but too low to be valvetrain.

Also I've got an m20 for sale if you do need one Jon, picked up a parts car.

[E34 530]

I know the exact sound you're talking about Jon, sounds like the typical m20 and eventhe m30 in my 535is sounds the same way, almost like a sewing machine, correct? I wouldn't worry about it. My friend Karl's e30 had a rod knock in his m20,and believe me you can def. hear it. :p

[winfred]

well i hold no definite yes it's good as i have/will never see/touch/hear the car but it's likely good, you can adjust cold but you'll get a better adjustment hot and its not that bad, you can tell how hot it is getting by touching the valve cover and shut it down when it starts to get as hot as you are willing to deal with

[Ross]

Agree with adjusting hot. Set to the loose side of specs too. They wont idle for **** when tight enough to be quiet.
As far as discerning a rod knock; if you rev it and it rattles on the over run then it's probably in the bottom. Vrooom, rattle, rattle, rattle. Does that make sense?

[Ross]

Well Mom, it sounds like a goner. However I have this "other" engine.....

[M20Turbo]

well i hold no definite yes it's good as i have/will never see/touch/hear the car but it's likely good, you can adjust cold but you'll get a better adjustment hot and its not that bad, you can tell how hot it is getting by touching the valve cover and shut it down when it starts to get as hot as you are willing to deal with

I have always been told to adjusted the valves cold, I will have to try doing it hot next time and see/hear if there is any difference. I have also found if I take out the spark plugs and move the engine by hand vs bumping the starter, it will take less time and cut down on the wear and tear of your starter. (my 2 cents)

Jon, I have been following your progress on your turbo project, keep up the good work.