MAHLE cam bearings too big

[TIB3300]

Hello peeps

Has anyone had any problems with MAHLE bearings?
I have ordered some cam bearings from rock autos, and they seem way too big and they rattle around on the cam.
I have made a short vid if anyone wants to see

Thanks

[mopar_mark]

I’ve never heard of oversize Cam bearings, I can only assume they have sent you the wrong ones. If that’s the case, quite a coincidence that the O/D was the correct size.
Can you cross reference the part number from the box they came in, to verify what you have

[Dave999]

if this is based on taking out of box and trying against a cam journal then

they might rattle now
but may not once squashed into the hole,
and remember they are all different sizes front to back
big at front and smaller at the back
other way round you'd not be able to put the cam in
match each bearing to its journal and see if it fits better

if they are in the block they must be in the right position cos they usually don't fit in the wrong place, well they don't on a long 6 cylinder which uses the same bearings bar 1 or they are numbered or something.

** remebered... they only fit on the tool 1 way in the correct order, draw lines in felt pen line em up get out the mallet**


and it would imply an issue with them or the cam


BUT sometimes rockauto gets it so very very wrong...
and
sending it back is expensive
and
nobody responds to any complaint ever

their attitude seems to be, you got it cheap, whaddya expect...like it or lump it mate

i reported to them that their parts numbers for manual steering box seals was wrong about 3 years ago. after being sent 2 saucer sized seals that had nothing to do with steering boxes
its still wrong
and a found a post on a message board indicating it had been wrong for 6 previous years

Dave

[Dave999]

PS
1) you will need to make beg borrow or steal a cam bearing fitment tool. **
2) if you have the option to keep the originals then keep the originals they were fitted and finished in the block with a big hone

** long bar with profiled pucks on it that have s step in them they fit closely the inner diameter of the bearing and have a step that is the same the outside Dimeter.

front bearing goes in just far enough to totally uncover the oil hole. the place where it goes is wide enough nearly for 2 bearings
from what i remember the bearing fits about 2/3 back but the oil hole is the key

obvious you start with the rear one its the smallest

[Dave999]

PPS do not knock the cam plug out at the back unless you have a new one. it does not come in the box of core plugs

[TIB3300]

"I’ve never heard of oversize Cam bearings, I can only assume they have sent you the wrong ones. If that’s the case, quite a coincidence that the O/D was the correct size.
Can you cross reference the part number from the box they came in, to verify what you have""

I must admit I cant find any over size ones
Ive not fitted them yet, as with this build . i have now figgerd nothing is at it seams
Spent over an hour the other day scrolling the net, and yep supplied correct .I did get them from rock autos but summet list the same numbers .

if this is based on taking out of box and trying against a cam journal then they might rattle now


The ones taken out are a lot better fit, even though badly worn

and remember they are all different sizes front to back

if they are in the block they must be in the right position cos they usually don't fit in the wrong place,,
Not fitted yet

and it would imply an issue with them or the cam, I have tried them on two cams, both rattle


BUT sometimes rockauto gets it so very very wrong...


I must say Rock Autoes have been great!

I told them, and they sent me a new set out strieght away

But alas these dont fit either

[TIB3300]

Removing tool

Made one already Dave

How the hell can you get the rear/ small one out without removing the rear plug?

[Dave999]

I have a feeling i just left it in as i could not find an appropriate cam plug

Mine was a dead motor obsolete from 1982 onwards and only made in Oz yours was sold the world over so parts easier to get

if you have one then go ahead knock it out



the cam bearings you took out of the block are already compressed to the size of the hole they were in.
the ones out of the box brand new have not been compressed so they will be bigger When Dry and than when installed

fitting to the block compresses them to a slightly smaller diameter inside and out we are talking a fraction just enough to take a sloppy fit to a fit with nearly minor resistance

so unless the clearance is massive the gap will be removed by installation and application of assembly lube and later oil

but if they are rattling like curtain rings on a curtain pole you have an issue! If they are just a little bit clicky when new and dry on a brand new cam journal that will be gone when they are squished into the hole.

in fact some have the other problem
they can't get the cam into a bearing that fitted out of the box but is too small when installed in the block

believe i started at the back and pulled the bearings in, so that the bearing side/edge/face that took the force of installation was not the one the cam had to pass through first. saves any over exuberance causing a gall or bent edge that would stop installation stone dead at an awkward point


Dave

[Dave999]

unless there is a difference in bearing for roller cam blocks to flat tappet blocks...i'm not aware of one but there might be

in which case you need 318 LA bearings

not 318 magnum bearings

Dave

[TIB3300]

Thanks Mr

As I now have two sets I will trial fit one set

[Blue]

When you change cam bearings you need to use an old cam to ream them to size, they will be too tight otherwise.

[TIB3300]

I have a feeling i just left it in as i could not find an appropriate cam plug

Mine was a dead motor obsolete from 1982 onwards and only made in Oz yours was sold the world over so parts easier to get


The cam bearings you took out of the block are already compressed to the size of the hole they were in.
the ones out of the box brand new have not been compressed so they will be bigger When Dry and than when installed

Fitting to the block compresses them to a slightly smaller diameter inside and out we are talking a fraction just enough to take a sloppy fit to a fit with nearly minor resistance

so unless the clearance is massive the gap will be removed by installation and application of assembly lube and later oil

but if they are rattling like curtain rings on a curtain pole you have an issue! If they are just a little bit clicky when new and dry on a brand new cam journal that will be gone when they are squished into the hole.

in fact some have the other problem
they can't get the cam into a bearing that fitted out of the box but is too small when installed in the block

believe i started at the back and pulled the bearings in, so that the bearing side/edge/face that took the force of installation was not the one the cam had to pass through first. saves any over exuberance causing a gall or bent edge that would stop installation stone dead at an awkward point


Dave

Well bugger me!!!!!

I knew there was a reason I joined this club
Thanks Dave
Fitted them all is good , I fitted just one and checked it , and you were rite. It sqished it up

[TIB3300]

When you change cam bearings you need to use an old cam to ream them to size, they will be too tight otherwise.

Thanks Blue
I had read this and yes its a bit tight, but I can turn it with a spanner. As you said stick and old cam in there first

[Blue]

I'd say if you can't turn it easily with the sprocket bolted to it it's too tight. You are not just reaming the bearings to size, you're also ensuring they are in line.

[MattH]

I have a fitting tool somewhere, from when my local engineers did this job for me.

That cam shaft came in useful then Blue.