Start up crank knock/rattle

[daverclasper]

An age old chestnut, I know with various opinions about, whether it's a problem?.

Aside from that I'm intrigued by an article in the Courier (May 88, page 16), where a member had stripped down some engines with start up rattle and found crank journals and bearing, good, conversely, some engines with no rattle had shot crank/bearings.

Interested, as how can this be the case? 

[Colin Lindsay]

It's a bit like a diff that doesn't leak - is it well sealed, or is there no oil left? I don't think there's a hard and fast rule about engine knock; the article explains why it happens, but there will always be engines that are worn and don't knock, for one reason or another - maybe a good oil pump that circulates very quickly coupled with a good anti-drain filter, whilst an unworn engine may have a worn or cheap pump that isn't as efficient. You just never know until you have the engine in front of you.

[daverclasper]

Sounds the most logical Colin, as well as factors like, how long does it take to start etc.

Always sounds so gruesome, that noise, though now I crank without choke for a while. Just seems mentally, more fluffy and cosy 

[Peter Truman]

I think the supposed death rattle on start up with the 6 potter upsets most of us even tho' on all accounts no damage is done, it's upsetting.

With my Vitesse I was having problems with my mechanical fuel pump priming up even with a replacement new pump and having replaced all the fuel lines, so I bit the bullet and fitted an electric pump next to the tank in the boot, the issue then was as soon as you turned on the ignition the pump was priming and turning the engine over with the choke in/off resulted in fouled plugs, solution a dash mounted interrupt switch and light so I could turn the engine over getting oil circulating (count of 12) before switching the elect pump on and a couple of sec's later brrmm and no rattle or plug fouling, maybe those NKG plugs will last longer now. If the car hasn't been started for a while I do turn the engine over by hand first to ensure nothings tight or seized. 

There is/was a member called "GT6, Marcus" I think, who had the ultimate solution a pressurized oil tank as part of the engine lube system mounted on the bulkhead that fed oil to the engine when the ignition was turned on using a series of solenoids, pressure gauges etc, I have pic's somewhere, a lot of engineering but well thought out!

[Clive]

10 hours ago, Peter Truman said:

I think the supposed death rattle on start up with the 6 potter upsets most of us even tho' on all accounts no damage is done, it's upsetting.

There is/was a member called "GT6, Marcus" I think, who had the ultimate solution a pressurized oil tank as part of the engine lube system mounted on the bulkhead that fed oil to the engine when the ignition was turned on using a series of solenoids, pressure gauges etc, I have pic's somewhere, a lot of engineering but well thought out!

Accusump are the ones you can buy. Nothing difficult about plumbing, just cinnects to teh oilways at you point of choice, and a switch to open the solenoid just befor starting and indeed switch off before stopping the engine (to make sure the accusump is pressurised, ready for the next start)

Years ago there was a clever chappie in the local area who made a little electric pump to pressurise the oil system before starting. Simply turned it on for a few seconds before turning the key. Still struggling to see how he made it, I think he used a 12v tyre compressor as the basis.

[johny]

I think the duration and level of the rattle is, logically, related to the bearing and oil pump clearances. Without regrinding I recently replaced big ends, mains plus pump (later higher capacity type) and theres a substantial improvement. Now with a bit of turning on the starter before firing theres none...

[Pete Lewis]

i often say its knocked on starts from long standing for50 years and they only lasted this long  , everyone rattles on about the filter draining  but few realise the gallery and crank journals also drain by simple gravity and the bearing clearances  its the whole system that needs a charge to solve a not a problem problem

each to their own paranoia i guess    just fire her up let it idle a few seconds and drive the darnn thing..... save the hassles for a real problem 

pete

 

 

[dougbgt6]

I have the death rattle, but I expect another 20 years, same as my Triumph. 

Doug

[Pete Lewis]

theres no death involved  just the rattle    even babies get one of those 

just as much trouble and last 50 years as well 

[ahebron]

On 04/02/2022 at 10:34, Peter Truman said:

I think the supposed death rattle on start up with the 6 potter upsets most of us even tho' on all accounts no damage is done, it's upsetting.

With my Vitesse I was having problems with my mechanical fuel pump priming up even with a replacement new pump and having replaced all the fuel lines, so I bit the bullet and fitted an electric pump next to the tank in the boot, the issue then was as soon as you turned on the ignition the pump was priming and turning the engine over with the choke in/off resulted in fouled plugs, solution a dash mounted interrupt switch and light so I could turn the engine over getting oil circulating (count of 12) before switching the elect pump on and a couple of sec's later brrmm and no rattle or plug fouling, maybe those NKG plugs will last longer now. If the car hasn't been started for a while I do turn the engine over by hand first to ensure nothings tight or seized. 

There is/was a member called "GT6, Marcus" I think, who had the ultimate solution a pressurized oil tank as part of the engine lube system mounted on the bulkhead that fed oil to the engine when the ignition was turned on using a series of solenoids, pressure gauges etc, I have pic's somewhere, a lot of engineering but well thought out!

I fitted a similar thing to my parents Alvis 12/50 Ducktail.
Originally it was a gravity fed tank above your feet feeding twin SUs, that wasn't the best.
We fitted a tank in the tail and ran an electric pump through an oil pressure switch on the block, no oil pressure no start.

That car made its way back to the UK via Australia in the last couple of years.

[NonMember]

4 hours ago, ahebron said:

We fitted a tank in the tail and ran an electric pump through an oil pressure switch on the block, no oil pressure no start.

I think the carburettor engined Montegos did that, too.