Aluminum blocks and oil leaks....

[Dave Wood]

I would have to agree with Ron. As a 30+ year motorcycle and exotic car tech, I rarely saw an oil leak on a motorcycle that had anything to do with the material. I think, as pointed out, that many of the exotic car leaks have less to do with material than actual construction/design.While an american V8 design has only a few possible leak areas, take a look at any one of a number of "exotic" engines. They often have cam holders that are separate from the heads, external plumbing or other mechanical enclosures. Each one of those items make leaks almost a given at some point. I think it has more to do with all the extraneous devices that are on those engines than the aluminum that they are constructed from. I, of course, realize the thermal expansion properties and the more little pieces that are used and need sealed the more likely that they will be affected by it.

 

[Bernard]

Interesting subject! As I have built a SBF aluminum block I can tell you that it is true, there are several oil leak possibilities. However, as it was previously mentioned, if you have a carefully building operation, you will obtain a good result.
First of them, we have to keep in mind that aluminum SBF are only semi finished block and you have to perform several machining operations to adapt it to your main components. For a good oiltightness, the main point is to machine the oil pan deck plan at the right value. You have to install the distribution cover to do it and to compare with a gauge how much thousandths it will be necessary to mild to have exactely the same level between both parts (you have to refer to the distribution cover level). Then, you have to provide a pair of plates to adjust the rear end bearing (see picture here below). Last point regarding the oil pan installation: I like to use a one piece oil pan gasket. Next critical point is the valley between intake manifold and block. At this place, despite my separated cover plate, I use a complet silicon tube to be sur that oiltightness is performed properly. Regarding the oil dipstick, as I have a dry sump, I have installed a plug to solve the point

 

[Ron Earp]

Interesting subject! As I have built a SBF aluminum block I can tell you that it is true, there are several oil leak possibilities.

But..... none of them have anything to do with the block being aluminum. They have to do with the block being finished properly and machined properly, as well as being assembled correctly. The issues with an aluminum block Ford motor is the same with the iron block motor, careful attention to detail. Same for all motors.

Some motors are constructed in such a way that makes sealing difficult. The Lotus 9XX is horrible with many problem areas:

• Head design and engine lay over so that the exhaust cam tower is horizontal to the ground looking from the front of the engine with the seal pointed straight down. Seal will always be soaked in a pool of oil.
• Cam tower design is very difficult to seal with all round profiles to seal onto
• External oil pump with a lot of surface area to seal on a poor Lotus casting.
• External oil pump has three openings - one to block, one to dizzy, one to drive gear - lots of places to leak.
• Rear main seal has a crap design, even the "new" design is poor but loads better than the old rope seal

But it isn't because it is aluminum, it is because it is Lotus! And I am sure there are many horror stories out there with Ferrari, Porsche, Alfa, etc. designs where R&D money sort of run short on the design of things, castings, machining, etc.

Ron

 

[Bill Bayard]

I've seen a few leaks on aluminum engines that were due to poor machining, but some leaks were in spots where aluminum and steel were in "contact". The different thermal expansion and contraction rates of the two metals ended up being the ultimate culprit in those cases.



Bill

 

[Ron Earp]

But, in those cases good design/engineering can take care of the job. Having aluminum mate with iron or steel isn't a problem in and of itself, it just requires proper design and forethought in the engineering solution when the seals are designed or the expansion rates are considered in press-fit type work.

 

speaking of alloy blocks, the inlet manifold on an ls1 -- is it reversable ( end for end. steve

 

[Jac Mac]

speaking of alloy blocks, the inlet manifold on an ls1 -- is it reversable ( end for end. steve

Steve, Since they are the same head bank to bank( not left/right specific ) I dont see why not, no water passages to worry about either from what I can see. Might be some more LS-1 savvy guys than me around here though.

Jac Mac

 

[kiwi ka]

Talking of oil leaks, I am building a car with a Rover V8 and want to increase the sump capacity. Rather than weld on a bigger pan and possably get some distortion and promote oil leaks,what about running a seperate tank in the curcuit with the oil cooler.Any thoughts on this.

 

[flatchat(Chris)]

Add an "Accusump" (3-4 litre cap.) plus a cooler and that should be plenty -- (for a Rover) --probably need a windage scraper in the sump 'specially if you're going to drive it real fast:coolgleam:

 

[Jac Mac]

Talking of oil leaks, I am building a car with a Rover V8 and want to increase the sump capacity. Rather than weld on a bigger pan and possably get some distortion and promote oil leaks,what about running a seperate tank in the curcuit with the oil cooler.Any thoughts on this.

As the Rover has a Flat Pan Rail it would be fairly simple to mod the original steel pan as it has a double thickness pan rail. Just cut it 1" below the Rail and weld on your "new" full length pan-while the 'old' rail is bolted to an old scrap block of course. Your windage/scraper rail assy can then be sandwiched between block and pan with an extra gasket.

Jac Mac