clanking

rmcdonnell · 10-09-2011, 03:40 PM

Well, I thought I had lifter problems, and maybe I still do.
I took the cam tower off a couple of weekends ago, found a soft lifter in position 7, replaced it.
No obvious improvement.
Took the cam tower off last weekend, replaced two more lifters, both quite soft, numbers 5 and 6.
Still no obvious improvement. Put some atf in the oil, took for a fair drive, was definitely quieter, but the clank is still pretty obvious.

Hmmm. Got a stethoscope with a screwdriver bit in the end. Listening to the cam tower over each valve position, I can hear the lifters, they don't seem too bad. There is a bit of a rumble over the second pot. Listening to exhaust ports, all fairly quiet. Intake ports, fairly similar. Injectors all pretty quiet.

Don't think it's big end as the noise is coming from mostly from the top and back. Might be small end? Valve problem? What do I listen to, where, to tell if it is a small end? Really confused, as I thought it was a lifter problem, but I thought I would be identify which with the stethoscope.

Any way any useful suggestions appreciated.

cheers
Rissole

John_AZ · 08:04 PM

At first I was going to say rod bearings then I remembered this thread:

http://forums.rennlist.com/rennforums/924-931-944-951-968-forum/623191-solved-944-engine-noise-tap.html

Back to my first idea.

Is it a "clank", a "knock" or "chatter"

Have you tried lifting the car and using the stethoscope on the oil pan and check for rod bearing noise?

After using the ATF the oil and filter were changed right?

Are you using a conventional or synthetic oil?

GL
John

Timmay! · 10-09-2011, 04:47 PM

John,
FYI, the rennlist link is dead.

John_AZ · 10-09-2011, 08:02 PM

Quote:

Originally Posted by Timmay!

John,
FYI, the rennlist link is dead.

Again:

http://forums.rennlist.com/rennforums/924-931-944-951-968-forum/623191-solved-944-engine-noise-tap.html

John

rmcdonnell · 03:26 PM

Hey, thanks for the link John.

He had a bent intake valve on cylinder number three. My clank is fairly slow now I come to think of it, but timing the clank is a great idea, and compare it with the rpm. If it's half speed (and I think it is) it has to be OHC related.

I've had a good long listen with the stethoscope, and I think my lifters are not particularly noisy any longer, I think they were a bit before. Out of interest, which valve is in position six, intake or exhaust,? as with the stethoscope that's where the loudest knock related tapping is coming from, but it does sound deep, which is why I was suddenly wondering about a rod bearing.

Anyway, if it could be a bent valve I should probably pull the head sometime soon, but timing the knock has to be the first move and I should be able to get my oscilloscope to listen to it, and compare it with, say the firing pulse on a spark plug.

And I haven't done anything with the ATF yet, but will probably drain the oil this weekend. I'm not using her at the moment.

Quietly hopeful.
Cheers
Rissole.

rmcdonnell · 10-11-2011, 03:39 PM

OK, I just listened to his video.
The noise is identical, and the symptoms are the same, worst around the third cylinder.
So I probably have a bent valve.

So it's WYAIT time...

bring it on.
Cheers
Rissole.

John_AZ · 10-11-2011, 03:41 PM

Valves from the front of the car >E I E I E I E I

John

Slam · 10-12-2011, 06:30 AM

And on his car he had some valves: E I E I OH!

With a 'clack' 'clack' here and a 'clack' 'clack' there...

John_AZ · 10-14-2011, 04:39 AM

Quote:

Originally Posted by rmcdonnell

OK, I just listened to his video.
The noise is identical, and the symptoms are the same, worst around the third cylinder.
So I probably have a bent valve.

So it's WYAIT time...

bring it on.
Cheers
Rissole.

I hope you make many more tests and get more suggestions before you take the head off.

Bump

John

rmcdonnell · 10-14-2011, 09:42 AM

OK, thanks John, I should check a few more things out. But I am keen to get it sorted soon.

Check compression. While it still turns over. Ho Ho

Drain the oil, check the condition. (It will be thin with the ATF in it).
There is some white curdling in the filler tube, that I think is down to condensation over many years, no sign of water in oil or vice versa. I could do a leakdown test, or at least blow some air in the spark plug holes when the camshaft is off, and have a listen.

More checking of the camshaft and lifters.
Not sure about the AOS, need to do some reading.

But I'm pretty convinced it will turn out to be the valve, probably inlet as that's the most expensive! I think being unable to localise the souce with a stethoscope would be explained by it being a valve. It's a relatively slow clank, so again, pretty sure it will be half engine rpm, but I could record it, or get the scope on it.

The car has done 172,000 miles, so a top end overhaul will do it no harm, and it's cost me peanuts for the last 8 years. It's time the timing belt was replaced anyway, it's 6.5 years old, and has done about 25K miles. I'd like to check the rollers too.

Any suggestion on other vital checks appreciated.

Cheers
Russell

John_AZ · 10-14-2011, 10:06 AM

Way overdue!

I replaced the HG on my '87 2 years ago at about 115K.

I am going to replace the HG on my '88 within the next year - 64K.

The '87 and maybe the '88 were rumored to have faulty HGs. The '87 I am sure of.

On the '88, I only plan to change the HG gasket and valve stem seals. I am going to Lap the valves and clean up the head. With the intake off I can do the rest.

I will be checking for any tolerance the WSM requires.

You have gone beyond normal use on the HG. You must be doing all the maintenance and more before a problem happens.

GL
John