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Are Big End Bearings Expensive/difficult To Change?

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#1 WimpyMiniMan

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Posted 30 January 2016 - 12:17 AM

Hi I am currently in the process of taking my head to be refurbished and put back onto my current block and it whilst doing some researching I found a second hand engine on gumtree for approximately the same price. Now my question is do I get the head refurbed and then tackle the big end bearings on my engine ( I get knocking sounds whilst the engine isn't under load ), or do I just buy a new engine with working head and big end bearings trusting the buyer who says its in good condition? Also are big end bearings difficult to replace?

 

Cheers

George



#2 ANON

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Posted 30 January 2016 - 12:24 AM

you would seriously trust someone selling something on scamtree?



#3 tiger99

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Posted 30 January 2016 - 12:30 AM

Yes, they are very easy to change, but only if the engine is out, just follow the Haynes manual exactly. But first you need to check and accurately measure the crankshaft to see if bearing replacement is possible or if a regrind is needed.

 

For that reason, and the likelihood of other parts such as main bearings, pistons and rings, camshaft, oil pump, etc, all being worn, it is almost always more economic to have the engine reconditioned by a specialist. That is what they do all day, every day, and they know how to grind crankshafts to properly fit new bearings, etc.



#4 Cooperman

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Posted 30 January 2016 - 12:38 AM

The best advice with any old classic car is to never fit a used and unknown engine without stripping, inspecting & renewing the worn parts. Trust no-one selling a 2nd hand 'good' engine.

#5 WPD

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Posted 30 January 2016 - 12:38 AM

you would seriously trust someone selling something on scamtree?

I've bought numerous things from gumtree and its perfectly fine from my experience  O_O



#6 Spider

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Posted 30 January 2016 - 05:51 AM

Hi I am currently in the process of taking my head to be refurbished and put back onto my current block and it whilst doing some researching I found a second hand engine on gumtree for approximately the same price. Now my question is do I get the head refurbed and then tackle the big end bearings on my engine ( I get knocking sounds whilst the engine isn't under load ), or do I just buy a new engine with working head and big end bearings trusting the buyer who says its in good condition? Also are big end bearings difficult to replace?

 

Cheers

George

 

 

It sounds more to me like the whole engine should be removed and reconditioned. It's a total waste of time and money trying to do a little be here and then a little bit there. There will be many more things that will be found that will need doing other than just the big end bearings once it's taken apart and looked at properly.



#7 Fast Ivan

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Posted 30 January 2016 - 08:26 AM

Unless it comes from a known engine builder with a good rep and/or comes with a warranty tthen you're taking a chance. You could fit it and get 50,000 good miles from it but on the other hand it could be worse than what you have



#8 WimpyMiniMan

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Posted 30 January 2016 - 09:08 AM

I guess I'll just stick with my engine by the sound of it - only has to get me through until November at which point I'll have the funds to do a complete engine rebuild or even buy a new engine if the insurance doesn't go up to high for a 1275. Only problem is I don't have an engine hoist so I don't see how I could get the engine out to replace them. Seems like I should however since almost all the ancillaries on the car will be out.

#9 David128

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Posted 30 January 2016 - 09:21 AM

Back in the day a length of scaffold pole a bit of rope and 2 big assistants (girlfriend & mother) lol shouting up a bit down a bit to you to me  and the odd swear word !!!


Edited by David128, 30 January 2016 - 09:22 AM.


#10 monkey

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Posted 30 January 2016 - 09:39 AM

Depending on how cheap the 2nd hand engine is it may be worth fitting that while you take the time to recondition the original engine - or recondition the 2nd hand engine and live with the knocking from your original engine whilst doing so. At least that way the car can still be used.
Could you see the 2nd hand engine running / driving before buying?

#11 ChopperHarris

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Posted 30 January 2016 - 09:39 AM

Big ends normally make their presence known when under load.

Hi I am currently in the process of taking my head to be refurbished and put back onto my current block and it whilst doing some researching I found a second hand engine on gumtree for approximately the same price. Now my question is do I get the head refurbed and then tackle the big end bearings on my engine ( I get knocking sounds whilst the engine isn't under load ), or do I just buy a new engine with working head and big end bearings trusting the buyer who says its in good condition? Also are big end bearings difficult to replace?

 

Cheers

George



#12 WimpyMiniMan

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Posted 30 January 2016 - 11:35 AM

Big ends normally make their presence known when under load.


Hi I am currently in the process of taking my head to be refurbished and put back onto my current block and it whilst doing some researching I found a second hand engine on gumtree for approximately the same price. Now my question is do I get the head refurbed and then tackle the big end bearings on my engine ( I get knocking sounds whilst the engine isn't under load ), or do I just buy a new engine with working head and big end bearings trusting the buyer who says its in good condition? Also are big end bearings difficult to replace?
 
Cheers
George

I've heard they sound when the engine isn't under load - I may just do the head run the engine with the knocking and recondition another engine over time and install it when it's fully built. Are there any major consequences of running the engine with worn big ends?

Regards
George

Edited by WimpyMiniMan, 30 January 2016 - 11:39 AM.


#13 Cooperman

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Posted 30 January 2016 - 01:19 PM

It is not a good idea to run an engine with a big-end knocking. First of all it will badly damage the crankshaft and in a worst case it may cause a scrapped crankshaft or cause failure of a big end cap. If the cap failed the bits would drop down into the gearbox effectively scrapping it and a rod may go through the side of the block. Unwise in the extreme. If it's broke, fix it! 

If you want to run an old  classic car, as many on here have said repeatedly, you need to be either able to fix it yourself, or have the cash to pay a professional at around £40 per hour. Most of us are in the former group - I know I am as I couldn't afford to pay to have my Minis fixed professionally.



#14 ChopperHarris

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Posted 30 January 2016 - 01:32 PM

Big ends normally make their presence known when under load.


Hi I am currently in the process of taking my head to be refurbished and put back onto my current block and it whilst doing some researching I found a second hand engine on gumtree for approximately the same price. Now my question is do I get the head refurbed and then tackle the big end bearings on my engine ( I get knocking sounds whilst the engine isn't under load ), or do I just buy a new engine with working head and big end bearings trusting the buyer who says its in good condition? Also are big end bearings difficult to replace?
 
Cheers
George

You heard wrong. Put car in 4th with hand brake on, let clutch out gently as if trying to pull away...if you get a deep donk donk donk that's big end. Simulated by trying to go up a hill in the wrong gear. Whats your oil pressure? Two main things effect pressure..condition of pump or the resistance to force the oil through big ends. If the ends are worn the oil goes through easir, especially when hot = low pressure

I've heard they sound when the engine isn't under load - I may just do the head run the engine with the knocking and recondition another engine over time and install it when it's fully built. Are there any major consequences of running the engine with worn big ends?

Regards
George



#15 Ethel

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Posted 30 January 2016 - 02:52 PM

In my experience shot big ends are very predictable and worse under load, you can almost play a tune on them using the accelerator. If they are bad enough to knock I wouldn't be expecting to cure them by just fitting new shells.

 

Have you investigated other possibilities? Is the knock related to engine or road speed, does it happen out of gear or with the clutch in? Does engine temperature make any difference, what's your oil pressure like?







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