Engine rattle

[Billmack]

I've heard a sound like that from a loose piston

[rgh0]

Rohan, what is the best way to determine this please. Stethoscope?

Take the cam cover off and move each lobe in turn to the clearance measurement position. Check the clearance and then see if you can rock the follower in its bore by pushing down alternatively on each side of the follower. If you can feel it move then the follower and / or bore is probably excessively worn and could be causing the rattle

The only real way to tell if wear is outside specifications is to dismantle and measure but this quick test will tell you if you have grossly excess wear and normally you need this to get a follower to rattle.

cheers
Rohan

[2cams70]

Check if there's any change depending on whether the clutch pedal is pushed or not.

[Hawksfield]

Rick

When driving on the road is the rattle present when pulling under load up to 60 mph.
Or is it present on the over run only.

[hubrick]

Continuing to investigate with the cover off. I've found a loose cover on the fuel pressure indicator on the inlet to the carbs, I can rattle it around by hand, wonder if it's engine vibration that makes it rattle, that would be great! Any guidance on reinstalling the gasket - rtv it to the cover, grease the head?

Hawksfield

No, rattle not when pulling under load, when off of the accelerator at higher rpm.

2cams70

Pretty sure its with clutch in or out.

rgh0

only 72,000 miles on the car. cam followers were reshimmed at 70000 miles. The three lobes in the clearance measurement position are all in spec and the cam followers are solid, no rocking. Is it worth taking the car down off of the ramps and rolling it in gear to move the cams and check the other 5?

billmac

a loose piston would not be good!

sprintsoft

same comment as rgh0. Just reshimmed 2k miles ago, and 3 in position are good. PO put in new shims in several locations to get to center of spec range for clearances.

ericbushby

I found the diagram in the service manual and of course you/the group were right, 1/4" up and 1/4" down. I've adjusted it to that spec.

[ericbushby]

Hi Rick
I fixed the cam cover this way.
Wellseal on the gasket and on the cover upside down. left it quite a long time to evaporate and become sticky before closing, placed a flat board on top of the the gasket with weights on top. The following day fitted the cover with engine oil on the head and gasket. OK so far with no leaks and no squeezing out of the standard cork gasket. It has done eight months and 1000 miles since. We will see in the future if it is possible to remove the cam cover without having to fit a new gasket. Somehow I have doubts but until then it is good.
Eric in Burnley
1967 S3SE DHC

[rgh0]

Continuing to investigate with the cover off. I've found a loose cover on the fuel pressure indicator on the inlet to the carbs, I can rattle it around by hand, wonder if it's engine vibration that makes it rattle, that would be great! .....

rgh0

only 72,000 miles on the car. cam followers were reshimmed at 70000 miles. The three lobes in the clearance measurement position are all in spec and the cam followers are solid, no rocking. Is it worth taking the car down off of the ramps and rolling it in gear to move the cams and check the other 5?

I would check all 8 followers for clearance and rocking in their bores if you have the cam cover off, but the loose cover sounds like a strong possibility.

cheers
Rohan

[hubrick]

Hello everybody,
Well, it took me awhile to get back to reinstalling the cam cover. I checked the valve clearances, one exhaust was a little tight and one a little loose, so something else to do in the future. None of the cam followers "rocked", so that's not what's causing the rattle. Adjusted the chain to 1/4" movement up and down. Put it all back together, and wouldn't you know it, I still have the rattle. The fuel pressure gauge that I thought might be the rattle isn't, so I've eliminated several things that could have been but aren't the rattle, and I'm still searching for what is the rattle. In the mean time, knowing that the timing chain is good, I'll go back to driving again. Thanks for all the help with my questions, I'll press on.
Cheers,
Rick
70 Elan 0045K

[mbell]

Have you checked the bell housing cover? There is a removable plate that is held by a couple of bolts, could possibly rattle if it came lose.

[hubrick]

Hello All,
Well, after checking for leaks in my driveway after a short run of the engine, I took off on a long drive. Even though it sounded like the rattle was still there in the driveway, I never heard it while driving for an hour. However, when I got back, there was oil all over the inside of the engine bay. Apparently from the cam cover gasket I had just replaced. Thought I followed the recipe correctly - glued it to the cover with ultra black silicone, sat it overnight on a flat surface with weight on top of it to let the silicone harden, put grease on the surface of the head and non hardening sealant on the cam plugs, and then tightened the cover down to the head. Apparently not tight enough or wrong procedure - oil everywhere, haven't determined exactly where yet, but obviously at the front of the engine. I'll get to that today or tomorrow.
Cheers,
Rick
70 Elan

[Billmack]

Unfortunately the most common.rattle I have seen from inside the engine is a loose piston. This can be found at idle when its making the noise by removing the plug wires one at a time and the offender will change the noise in some way.

[2cams70]

Key thing is whether the noise happened and is increasing in intensity gradually over time or whether it occurred over a shorter period of time. Wear related noises such as piston slap and cam follower noises don't just happen overnight. On the other hand a loose exhaust and similar is more likely to occur over a shorter period.

My experience with piston slap is that it's far worse when an engine has been rebored with too much clearance between piston and cylinder. The piston to bore clearance naturally increases over time due to wear but in this instance clearance increase due wear causes much less noise compared to when an engine has been rebored incorrectly.

My theory is that in the case of natural wear the surfaces have worn in together so when the piston rocks in it's bore the impact force is spread over a wider area and hence causes much less noise than the case when it's a new piston in a freshly rebored cylinder and the clearance is wrong.

[HCA]

My experience has been that it is nigh on impossible to diagnose an engine rattle from an armchair as there are so many types of rattle, and the definition of rattle sounds can differ person to person.

Can you determine for sure if the rattle is from inside the engine or a more tinny sound from outside?

I think everything has been mentioned so far except bearing rattle - big/small end rattle is generally under load and mains (which is more of a rumble than rattle) is heard on cruising. Both, when starting to show, can come in and out at certain rpm. Has your oil pressure changed (decreased) recently? Is the noise the same hot and cold?

[steve.thomas]

I’ve read that the non-return valve between the inlet manifold and headlamp vacuum system can rattle as they have a ball bearing inside. There may also be a similar valve in line to the brake servo if you have one fitted.
Good luck
Steve