cylinder head dowels

[tom1979]

I see this posted about on the internet quite a bit, but cannot find the source. I've looked on RAVE and in the service/recall actions but cannot find it. Anyone know ?

From the workshop manual....
AFFECTED RANGE:

All Td5 derivatives within VIN ranges:
Discovery Series II (02 Model Year) 2A 736340 to 3A 793895
Defender (02 Model Year) 2A 622424 to 3A 647705

SUBJECT:
CYLINDER HEAD LOCATING DOWELS
Td5 engines fitted to vehicles in the above VIN range are fitted with plastic dowels to locate the cylinder head onto the cylinder block.

Land Rover Engineering has introduced steel locating dowels from the following VIN numbers:
Discovery Series II: 3A 793895
Defender: 3A 647705

INFORMATION:
If a cylinder head is removed from a vehicle in the above VIN range, the plastic dowels must be replaced with new specification steel dowels, which are now available from Land Rover Parts.

CAUTION:
Td5 derivatives prior to the above VIN ranges must not, under any
circumstances, be fitted with the new steel dowels. If steel dowels are fitted to earlier engines, cylinder head cracking may result. ​

 

[jamesmartin]

in what way, plastic dowels only fail when head has moved too much thats caused by heat not the strength on the dowel

 

[tom1979]

in what way, plastic dowels only fail when head has moved too much thats caused by heat not the strength on the dowel

I was looking for the source of the information, I wasn’t questioning it.

The dowels are only to locate the gasket and head, they’re not relied on for keeping it all there - if the head moves it’s not down to the dowels

 

[sierrafery]

Here it is, if you measure the hole's depht and ID on those heads which they say to not fit steel dowels you might find out that it's a bit less than on those which are mentioned so forcing steel in that hole under torque might crack it, i respect3d this bulletin when the head was changed and no issues, IMO not worth the risk just cos those who didnt care about the bulletin had no issues so far, that's why LR sais ''may" not ''will " :

 

[tom1979]

Here it is, if you measure the hole's depht and ID on those heads which they say to not fit steel dowels you might find out that it's a bit less than on those which are mentioned so forcing steel in that hole under torque might crack it, i respect3d this bulletin when the head was changed and no issues, IMO not worth the risk just cos those who didnt care about the bulletin had no issues so far, that's why LR sais ''may" not ''will " :

View attachment 178572

My thoughts exactly but I wanted to find the source of the information rather than quoting quotes from the internet.

Thank you!