Embarking on the unknown

Chaps, i am going to change my big end bearings on my own. i have never done this before. i will post how i got on and anything o think is help ful and maybe some pictures. the process i beleive i am going to use is.

1. Warm engine up to drain oil
2. Dosconnect the battery
3. Empty the oil out
4. Remove sump (pan)
5. Remove oil filter
6. Remove spark plugs to reduce compression
7. Loosen slightly all the con rod end caps.
8. Then one at a time undo end and remove that shell remebering how it came out (i believe there are oil ways in the shell, so need to replace in the right position)
9. Move the piston up a bit to remove the con rod shell (this seems easy, but i am sure its not)
10. Refit new shells with oil way right and primed with? anyone help??????????.
11. refit end cap and torq up the right amount(not sure what it is yet any help??
12. Each time making sure the engine still turns
13. fit new sump (pan) gasket
14. New oil filter
15. Fill up with oil
16. Job done

Not sure if this is going to work if anyone has got any pointers i would be very interested

basobomber said:

10. Refit new shells with oil way right and primed with? Anyone help??????????.

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stp

basobomber said:

Chaps, i am going to change my big end bearings on my own. i have never done this before. i will post how i got on and anything o think is help ful and maybe some pictures. the process i beleive i am going to use is.

1. Warm engine up to drain oil
2. Dosconnect the battery
3. Empty the oil out
4. Remove sump (pan)
5. Remove oil filter
6. Remove spark plugs to reduce compression
7. Loosen slightly all the con rod end caps.
8. Then one at a time undo end and remove that shell remebering how it came out (i believe there are oil ways in the shell, so need to replace in the right position)
9. Move the piston up a bit to remove the con rod shell (this seems easy, but i am sure its not)
10. Refit new shells with oil way right and primed with? anyone help??????????.
11. refit end cap and torq up the right amount(not sure what it is yet any help??
12. Each time making sure the engine still turns
13. fit new sump (pan) gasket
14. New oil filter
15. Fill up with oil
16. Job done

Not sure if this is going to work if anyone has got any pointers i would be very interested

Click to expand...

Make sure everything is immaculatly clean before you fit new shells. Shells have an index so cannot be fitted wrong. For assembly get a tin of Wynns or STP to lub shells and journals before re-fitting conrods and caps to crank. Does not run off like oil does. I might ask why you are fitting new big ends? If they are rattling the journals maybe oval. And if you have low oil pressure it is odds on the mains will be shot.

wammers said:

Make sure everything is immaculatly clean before you fit new shells. Shells have an index so cannot be fitted wrong. For assembly get a tin of Wynns or STP to lub shells and journals before re-fitting conrods and caps to crank. Does not run off like oil does. I might ask why you are fitting new big ends? If they are rattling the journals maybe oval. And if you have low oil pressure it is odds on the mains will be shot.

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I am convinced the bottom end rattle under load only, is the the big ends. i have not checked my oil pressure (don't know how) but oil light never comes on while driving, and on tickover all is well. for the price of new shells (about £20) i thought i would try it first. if it is little ends or the mainbearings then its engine out and a huge bill.

basobomber said:

I am convinced the bottom end rattle under load only, is the the big ends. i have not checked my oil pressure (don't know how) but oil light never comes on while driving, and on tickover all is well. for the price of new shells (about £20) i thought i would try it first. if it is little ends or the mainbearings then its engine out and a huge bill.

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May well be, but main reason big ends go is lack of lubicant caused by oil loss from mains. As oil goes through mains first then to bigends any oil loss at mains starves bigends. It may end in tears. Little ends make a tinkling noise rather like pinking. Bigs ends a knock and mains is more of a rumble.

wammers said:

May well be, but main reason big ends go is lack of lubicant caused by oil loss from mains. As oil goes through mains first then to bigends any oil loss at mains starves bigends. It may end in tears. Little ends make a tinkling noise rather like pinking. Bigs ends a knock and mains is more of a rumble.

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Cheers mate your description of the noise helps, and points to big ends. i have not had the car long, and by the state of it it has been stood up for a while, for example the rear brake pads fell apart when i striped the callipers down to check condition. there is surface rust on everything, just the kind that rubs off, and i am in the process of doing this.

May seem mad, but this is my 4th p38 and the newest one. 2000 4litre se on lpg, and one i want to keep, as i dont want to pay the huge road tax of a newer one, so i must get this one right, or start all over again, until i can afford another p38.

Lastly in your first post you mentioned journals? i assume these are grooves in the shell?

basobomber said:

Cheers mate your description of the noise helps, and points to big ends. i have not had the car long, and by the state of it it has been stood up for a while, for example the rear brake pads fell apart when i striped the callipers down to check condition. there is surface rust on everything, just the kind that rubs off, and i am in the process of doing this.

May seem mad, but this is my 4th p38 and the newest one. 2000 4litre se on lpg, and one i want to keep, as i dont want to pay the huge road tax of a newer one, so i must get this one right, or start all over again, until i can afford another p38.

Lastly in your first post you mentioned journals? i assume these are grooves in the shell?

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No, journals are the crank bearing surfaces. As in main bearing journals and bigend journals. If when you remove the old shells they are free from any scoring, but worn to the copper backing you may have a chance. But be aware the mains will be the same. If they are scored in any way the mains will also be the same also the oil pump. Your new shells will only be a temporary fix. A thicker grade of engine oil may keep the wolf from the door a little longer. Or a couple of cans of STP added to your standard
oil maybe even better.

Any wear will be obvious if you say there is a "Knock" present as soon as you remove the caps.
Wammers is spot on when he says that the Mains take first bite of the cherry-pressure wise, especially the thrust bearings. Any excessive clearance in the Mains/Thrust areas allows too high a volume of oil to escape and spill back into the sump thus starving the Big Ends of oil.
The crank journals should be unmarked and round to within .0015". They should be measured with a Micrometer NOT a Vernier in several places and the sizes checked against those given in RAVE.