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Knocking sound from Transmission

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mjobrien

mjobrien

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Had the 100 out for a short drive on the road yesterday and noticed a knock at about 50mph in high gear with O/D switch in the on position. Seems that the O/D is not engaging best I can tell.

The knock goes way at stop and even when I rev the engine. No knock in 1st or second, but I need to verify second. I checked the Oil and it was within 1/2 of the top on the transmission.

A lot more to trouble shoot, just thought I would put this out there and see if it sounds familiar? Knock is coming from trans for all I can tell.

My first thought is the O/D is kicking in and out at a high rate and giving me this knock????


Thanks,
Michael.
55 BN1
 
More info please. Are you saying you get no noise if you leave the OD off through all the gears? Do you get an RPM drop when you flip on the OD in 3rd or 4th? Please do the simple stuff first like checking your universal joints on both ends of the drive shaft for security. Is the noise steady knocking if you have a constant pressure on the accelerator? If you are convinced that it is a gearbox noise I'd pull the oil screen and check to see if it is making metal. Check for things that might not be tight and could make noise at higher speeds (muffler hangers, suspension in the rear, wheel hubs that are not secure, rear transmission mount for security and condition of bushing,lug nuts that hold the hubs on can back off etc. Let us know what you find.
I would think that if your OD were going in and out it would be more of a surge, and than a deceleration,as opposed to a knock. You would have to be right on the feather edge of OD operating pressure to get it to kick in and out rapidly, although I suppose if you had an accumulator leak it could be possible. Be sure you are reving the engine up to speeds you might use when you are driving before you eliminate it (rev it up to 3k for 5 or 6 seconds). Hopefully something simple.
 
This is painfully close to the situation I was in last fall. I was convinced a similar noise was coming from the trans. I had a knock that only appeared when the engine was under load. 3rd and 4th gear while accelerating. It didnt happen when the car was at rest and I reved the engine. I took the Trans tunnel off and drove the car with same noise only louder. It only appeared when the car was at operating temps.

Long story short it was a failed rod bearing on the #6 cylinder. The way I found it was to drive the car with the plug wire disconected from one cylinder at a time (cylinder not under load). I started at the #6 so it didnt take long to realize the problem. The noise didnt exist at all

Not sure if the 4cyl will even run on 3 but try. I believe the bell housing acted as a speaker to amplify the sound near the trans.

I hope for your sake this is not your problem but though I should share my experience.Stop driving the car thinking it is trans related. If this is your problem, save the crank.

Good luck
Kevin R
 
What is it with the #6 cylinder?!

I had the same noise on a trip back from Canberra earlier this year - only the main bearing slipped on #6 and I lost all pressure and drive and my poor BJ8 started making some hideous noises as she pulled over to the side of the road.

When the engine was pulled apart, it turned out that the rods were in the wrong order and also that the oil flinger was too close to the case and had overheated. My temp guage hadn't registered this but the drop-off in oil pressure was the first thing I noticed - before the noise. Keep an eye on it.

Saving the crank is the right thing to do. I know the engines are different but the principles must surely eb the same. Crank regrind = cheaper than crank replacement.

I also found that 5 exhaust valves and 3 inlet valves were bent and that the harmonic blanacer was in a bad way. All this within 1000 miles of buying my first Healey....if you pull the engine you may wish to check all of these things just in case they're related.

Best of luck mate - I hope the damage is limited to the one bearing!

Bob

Bob
 
Thanks for the input.... I'm going to look under the car for anything that might be doing this and as a last resort drop the pan and take a look. Any pointers on spotting a spun bearing?

Michael.
 
Michael

If it a sort of chattering sound as opposed to a stead knock knock knock, have a look at the limit switch - the one that does not allow you to get overdrive in 1st 2nd and reverse. Once the end is worn its curtains for the unit. Two checks inside the car as you are going along - 1) get out of O/D which you have done - noise goes away. 2) move the gear stick side ways to either promote the noise or possible it goes away if there is enough side ways travel to make up for the worn tip of the switch. Not sure where your switch is on the 100 but on the 3000 it is easily get-attable and you can check the end.

BVob
 
Michael:

Correct me if I am wrong..is this not a freshly rebuilt engine?


Pete
 
Pete, yep it is... I was planning on taking the pan off for a inspection and see what I can learn. the bottom end of this was rebuilt last year with less than 100 miles on it. Good oil pressure and never over heating (max 190)

I'm not sure where I may have gone wrong.

If it requires it to be readdressed, I'll do it myself this time.

Michael
55 BN1 with a Knock :frown:
 
A suggestion, if you have not sourced it to the lower end of the engine. Do a little more diagnosis before tearing things apart, that may not need tearing apart.

Pull each plug wire, one at a time, and see if the knocking noise changes. If the noise lessens in force then go after whichever particular plug/cylinder was disabled.

Get a stethoscope, mechanics stethoscope can be purchased at most major parts houses, all tool trucks. That can help to pinpoint where the noise is coming from.

Is the noise commensurate with engine rpm, upper engine area(twice what crank speed is) or lower engine, crank speed? Does the noise change when you depress the clutch pedal, or select different gears? Does the noise change when you decelerate, i.e. "goose" the engine and let it return to idle? These are all things that can be explored before disassembly to focus on source of noise.
 
I would second Ron's suggestion,as the noise doesn't appear in 1st and 2nd or at idle or when revved stationary the engine is probably the last thing to look at.I suggest you get someone to drive the car and from the passenger seat try to locate area from which the noise is coming from,stick your ear to the gear stick to listen to the inards of the gearbox once your sure where the noise is coming from and how it comes in ,ie:- just with overdrive or just in top etc,then swap round and see if both of you agree and then start looking in that area. Don't forget that noise can be transmitted through the propshaft from the back .An hour or so's analysis can save a lot of unwanted work.
 
mikespain said:
I suggest you get someone to drive the car and from the passenger seat try to locate area from which the noise is coming from,stick your ear to the gear stick to listen to the inards of the gearbox
Click to expand...

:lol: That sure will look funny to anyone you may pass on the street. Maybe a member of the opposite sex should do the driving to keep up appearances. :smirk:
 
Michael:

Always think simple first..

Couple weeks ago had "knock" from the rear end. Had several experts listen to it. The majority said rear end issues..

CAUSE: Loose bolts on the splined hub. (had a shop replace the rear wheel seals last winter, must have not tightened them enough )...first work that I had hired out in years.

Pete
 
HEALEYJAG said:
CAUSE: Loose bolts on the splined hub. (had a shop replace the rear wheel seals last winter, must have not tightened them enough )...first work that I had hired out in years.

Pete
Click to expand...
Hi Pete,
If you're talking about the 5 nuts that attach the hub, they are lock nuts. If they have been taken off a bunch of times, they'll loose the locking feature. I'd suggest either locktite or new nuts if that's the case.
 
Yep...thats what we did....appreciate the info though!!

Much obliged:

Pete

Its 80 here in Ohio ..perfect Healey weather...went for a LONG drive...

Interesting I have yet to see a Healey on the road all year long.Except at shows..ITS A SHAME!!!
 
Thanks for the input, I did pull the pan first to see if anything was up. Well a little metal in the oil is the story of the day. Small particles of what appear to be metal and brass?

Looks like something failed for sure, all the connecting rods appear OK but I need ot take a closer look and put a little strain on them to see if any are loose.

This noise was only present in high gear at 50mph under load and from the lower right side of the passenger foot well based on my last drive. The U Joint all seem tight, the rear end ha some backlash but nothing to cause this I think. Also the trans seems to work as required with the exception the O/D might not be adjusted right (throttle switch issue I think)

So far nothing pulled apart that can't be put together in a few hours but I'm getting close to just yanking this engine. I need to talk to the shop that did the Motor and get their input on this as well.....


Michael.
 
Michael - A little bit of brass in the oil is more or less normal, although it can suggest a spun bearing. It can also suggest worn thrust washers. Unfortunately with the BN1/BN2 a spun bearing means pulling the motor to get the caps off.

Check one thing - pull the rocker cover and look for bent push rods. This can also cause knock-like sounds and could also explain the brass if the rocker arm has seized. This happened to my Atlantic (same motor) a while ago and I could have sworn the noise was a spun bearing but in fact it was just a bent push rod. Sent the rocker to www.rockerarms.com and it came back looking like it was new from the factory!
 
I also have a rattling (ticking) noise on my overhauled engine (7.000 miles ago) and it seems to be coming from cylinder number 6.

It starts once the engine is warm and is most noticable in low revs.

Three different people have suggested that it could be a pushrod or a tappet.
The noise is not coming from the lower part of the engine but more around the middle.

Although I know and understand the basics, I would like to know more on how to change a rod and or tappet and what ot watch out for specifically. For ex, can a new tappet be simply installed or will it have an effet on the camshaft?

I'm not saying I'll undertake this job myself (if it turns out to be too complicated), but I do want to learn more about how this is done.

Looking forward to all of your info
 
Actually, replacing a tappet is a pretty easy thing to do and can be done in any home garage. You just have to loosen the rocker pedestals just enough to pull out the push rod then take off the ali tappet plate and pull out the tappet with a screwdriver or bent pick. Put in the new tappet (with cam lube w/ ZDDP on the bottom of the tappet) and presto change-o you are off again. I could probably do the whole job myself in less than an hour.

... Or you could spend three hours driving to the mechanic, discussing it with him, dropping the car off, picking it up later and having him charge you for his time after you argue with him about the $100/hr shop rate!

:crazyeyes:
 
Update:

Dropped the pan, nothing looks out of place. Checked end clearance on all rod ends – all within spec. Checked Pushrods, all nice as new. Reinstalled the oil pan, refilled to the tippy top and no knock on one test drive. I’m going to test drive with wife (need to duck under a little) and see if I can hear this knock.

No Knock – off to body shop
Knock – Off comes pan and on goes new rod end bearings after crank inspection.

I thought simple things first… Only thing that might have changed is 1/2 quart of oil more now than before?

Michael.
 
Update - Looks like all the rod bearings are slightly scored and number 2 and 3 show signs of a fair amount of contamination. No color change or disfiguration to indicate heat or over stress. Needless to say I'm now forced with considering taking this engine out and going back over it. The amount of scoring would indicate that the shop put it together in a sand storm or just didn’t bother grinding the crank down.

After inspection of the old bearings I'm beeting they just ignored the journals, I can’t wait to see what the mains look like.....


Michael
55 BN1 with the lower end blues!
 
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