Lotus Elan

Engine rattle

PostPost by: hubrick » Mon Oct 25, 2021 5:19 pm

Hello Elan folks,
My 70 Elan has developed an engine rattle. Usually from 2000 to 2500 rpm. More steady now, but initially it was only when decelerating from higher RPM. I've looked all around above and below the engine, took off the fan belt to make sure it isn't the alternator or water pump, then finally concluded it must be the timing chain. I've read through many prior posts about it, and it sounds like adjusting the tensioner should have helped. It didn't.

Using 1/4 turns each time, I progressed to where I had two turns of adjustment and the rattle didn't seem to change much at all, might have gotten worse. I took a video, but it won't let me attach the mp4 file, at 1 3/4 turns. The rattle sound is now faint at idle too, you can hear it a little in the video. At that point, I removed the cam cover and found the timing chain to be very tight, so practically no play at all. I backed off the adjuster the two full turns and now I have just slightly less than 1/2" of play in each direction.

So I'm thinking that the rattle sound isn't the timing chain. Does that sound right? Any ideas what else I should look for before putting the cam cover back on?

Thanks for the help.

Cheers,
Rick
70 Elan 0045K
hubrick
First Gear
First Gear
 
Posts: 38
Joined: 20 Mar 2020
Location: Baton Rouge, LA

PostPost by: h20hamelan » Mon Oct 25, 2021 5:27 pm

You could try a stethoscope or more simply a funnel and hose, the latter probably better at this point.
Can you be sure its front of engine. Metal on metal sound/vibration travels easily.
For sure the exhaust is not the culprit?
Born, and brought home from the hospital (no seat belt (wtf)) in a baby!
Find out where the limits are, and start from there
Love your Mother
Earth
User avatar
h20hamelan
Coveted Fifth Gear
Coveted Fifth Gear
 
Posts: 1258
Joined: 25 Sep 2010
Location: RACECAR spelled backward, is——RACECAR!

PostPost by: Slowtus » Mon Oct 25, 2021 6:01 pm

h20hamelan wrote:You could try a stethoscope or more simply a funnel and hose, the latter probably better at this point.
Can you be sure its front of engine. Metal on metal sound/vibration travels easily.
For sure the exhaust is not the culprit?


Excellent point, we have all chased noises and lacking a funnel or hose, simply a longish screwdriver.

Pop the hoonnet off and have a friend hang their head out the window.

Yes, seriously.

PS, adjust your timing chain to spec as well, since you have fiddled with it.

PPs, this may (or may not) help.

https://www.bellperformance.com/blog/di ... ine-noises
Slowtus
Third Gear
Third Gear
 
Posts: 327
Joined: 22 Sep 2017
Location: Canada

PostPost by: ericbushby » Mon Oct 25, 2021 6:31 pm

Hi Rick,
I don`t think I can help with your rattle, but it sounds like you have not set the chain tension correctly.
Smack the chain downwards between the camshaft sprockets with a piece of wood or similar.
This moves all the play to that point. You should have half an inch total up and down movement not 1/2 " each way. which would be a total of 1 inch.
Good luck
Eric in Burnley
1967 S3SE DHC
ericbushby
Coveted Fifth Gear
Coveted Fifth Gear
 
Posts: 1097
Joined: 13 Jun 2011
Location: east lancashire

PostPost by: richardcox_lotus » Mon Oct 25, 2021 6:32 pm

The only other quick suggestion is.... is your dipstick in the right way round ?

If it’s out by 180 degrees, it rattles more.

Been there; done that.

Regards
Richard
Richard
'72 Sprint
richardcox_lotus
Coveted Fifth Gear
Coveted Fifth Gear
 
Posts: 1266
Joined: 11 Jul 2004
Location: Kent

PostPost by: hubrick » Mon Oct 25, 2021 7:25 pm

Thanks all, wow rapid response from lots of you, appreciate it.

I wrote a response on my phone but when I pressed submit it didn't do anything. So now I'm back home. Here's that first response to h20hamelan.

"Thanks. Yes I've tried a stethoscope before adjusting the chain. Nothing found, probably just didn't put it on the rattling component. Forgot to mention that. It does sound like it's coming from the front of the engine, or maybe underneath the carbs, but hard to tell. I've been under the car while my brother revved it and got it to rattle, and I don't see anything, particularly the exhaust, which is what I thought it was, rattling."

slowtus

Seems like if I can hear the rattle standing by the car with me revving it at the carbs, how will a passenger hanging his head out the window help?

ericbushby

I've seen a diagram that shows the proper amount of tension on the chain. It clearly showed 1/2" from the top of the chain to the highest point, and 1/2" from the bottom of the chain to the lowest point. You're saying it should be half of that movement, so only 1/4" in each direction? I know I've been there while I was adjusting it, and the noise never did go away. When I took the cover off, there was essentially no movement in the chain at all, and I turned it back two turns to get it to where it is now.

richardcox_lotus

Which is the right way around on the dip stick?

Anybody heard that kind of rattling from the distributor with an electronic ignition magnet set trying to come apart. Someone has suggested that to me.

Trying to identify something else to check before I reinstall the cover with the new gasket, plugs, seals that arrived today.

While we're at it - I've read about how best to seal the cam cover. Do we really attach it to the cover with RTV and just put grease on the head? Seems like that lowest point at the head would be the most prone to oil leakage.

Cheers,
Rick
hubrick
First Gear
First Gear
 
Posts: 38
Joined: 20 Mar 2020
Location: Baton Rouge, LA

PostPost by: Slowtus » Mon Oct 25, 2021 8:57 pm

hubrick wrote:Thanks all, wow rapid response from lots of you, appreciate it.



slowtus

Seems like if I can hear the rattle standing by the car with me revving it at the carbs, how will a passenger hanging his head out the window help?



Cheers,
Rick


The rattle may become more/less noticeable when the engine is under load - being driven, hence my suggestion
Slowtus
Third Gear
Third Gear
 
Posts: 327
Joined: 22 Sep 2017
Location: Canada

PostPost by: hubrick » Mon Oct 25, 2021 9:03 pm

slowtus

aaah, yes, that does make sense. however, in this case, the rattle seems to be the same while sitting in the driver's seat or standing next to the engine bay.
hubrick
First Gear
First Gear
 
Posts: 38
Joined: 20 Mar 2020
Location: Baton Rouge, LA

PostPost by: Slowtus » Mon Oct 25, 2021 9:08 pm

hubrick wrote:slowtus

aaah, yes, that does make sense. however, in this case, the rattle seems to be the same while sitting in the driver's seat or standing next to the engine bay.


The same when being driven?

Is it possible it is on the intake side? rattling venturis caused by loose clamps - yes that IS a stretch but still possible.
Slowtus
Third Gear
Third Gear
 
Posts: 327
Joined: 22 Sep 2017
Location: Canada

PostPost by: elans3 » Mon Oct 25, 2021 9:10 pm

If the car is still running the original 2 blade fan, check the rivets in it haven't come looks, and while you're at it, check that the cranl pulley is still tight. If it's still on the original dynamo, remove the fan belt and spin the pulley. A goosed dynamo bearing can sound like a rattle too. Mine did.....
Current :- Elan S3 DHC SE S/S 1968,
1963 Alfa Giulia Ti Super Rep.
Previous :-
Elan S3 DHC SE SS 1968,
Elan S3 DHC S/E 1966
Elan S3 FHC Pre-Airflow 1966
elans3
Third Gear
Third Gear
 
Posts: 381
Joined: 12 Sep 2003
Location: Doncaster, South Yorks.

PostPost by: hubrick » Mon Oct 25, 2021 10:01 pm

slowtus

yes, same when driving.

yes, seems like on the intake side. i'll check carbs/venturis for loose clamps

elans3

no, original fan is gone. i'll check the crank pulley. running an alternator, have already checked alt and water pump, rattling noise same when fan belt is off.

So, several suggestions for me to try. I'll check those. Nothing inside the head though. Looks like I'll tighten the chain to the 1/4" up and down movement contrary to the diagram I saw, reinstall the cover, and start it up and try to identify the rattle some more.

Thanks for all the suggestions. Anybody think of any more, send them my way.

Cheers,
Rick
hubrick
First Gear
First Gear
 
Posts: 38
Joined: 20 Mar 2020
Location: Baton Rouge, LA

PostPost by: ericbushby » Mon Oct 25, 2021 10:21 pm

Hi Rick,
Yes I think I know the diagram you mean, and this has been discussed here before.
The suggestion is that the drawing is done by a draughtsman not an engine man so is not necessarily accurate, but the text at the side of the drawing clearly says 1/2" total movement.
Eric
ericbushby
Coveted Fifth Gear
Coveted Fifth Gear
 
Posts: 1097
Joined: 13 Jun 2011
Location: east lancashire

PostPost by: rgh0 » Mon Oct 25, 2021 10:23 pm

Worn cam followers can also create a "rattle" as they rock in the sleeves.

cheers
Rohan
User avatar
rgh0
Coveted Fifth Gear
Coveted Fifth Gear
 
Posts: 8052
Joined: 22 Sep 2003
Location: Melbourne, Australia

PostPost by: h20hamelan » Mon Oct 25, 2021 10:31 pm

Rohan, what is the best way to determine this please. Stethoscope?
Born, and brought home from the hospital (no seat belt (wtf)) in a baby!
Find out where the limits are, and start from there
Love your Mother
Earth
User avatar
h20hamelan
Coveted Fifth Gear
Coveted Fifth Gear
 
Posts: 1258
Joined: 25 Sep 2010
Location: RACECAR spelled backward, is——RACECAR!

PostPost by: sprintsoft » Mon Oct 25, 2021 11:36 pm

Hi Rick,

Don’t miss the opportunity to measure your valve clearances whilst you have the.cam cover off, that will eliminate a possible source of your rattle

Iain
72 Sprint - 0363E
74 S130/5 - 1931L
sprintsoft
Third Gear
Third Gear
 
Posts: 236
Joined: 18 Mar 2019
Location: Swansea, UK
Next

Total Online:

Users browsing this forum: ericbushby and 12 guests