Technical Aluminum Oil Pan

[Richenrygarcia]

It is hot in southern Italy. I want to install a 3.5L aluminum oil sump on my 650cc engine to assist in keeping things cool.

Question: Do you recommend I use silicone hi-temp gasket maker or a pre-formed gasket to mate the oil pan to the block?

I have a tube of red gasket paste and a fiber/felt (not cork) gasket. When I look on the internet for recommendations, I can't find one consistent answer therefore I'd like to know what you experts have used successfully.

Thank you.

 

[Toshi 975]

Do not use a gasket with an alloy sump as you will loose any potential strengthening of the crankcase. Use a little good quality instant gasket but do not let too much get inside the sump as it could block the oil ways.

 

[the hobbler]

Toshi is absolutely correct---if you are fitting the sump to help stiffen the crankcase, do not use a gasket--just a liquid seal. I have fitted a gasket between my (aluminium) sump and the crankcase---the 'ruberoid' version. I would not advocate the 'cork' version under any circumstances. If you decide to fit the sump "sensa" gasket, I would suggest that you use one of the modern 'gasket goo' dispensers. Euro carparts sell 2 pressurised dispensers that have a 'squeeze' trigger to regulate the flow of the sealant. 1 is made by 'Wynns' (black gasket maker---a.k.a. sealant 57680) and the other is by 'Triple X' (easy gasket---part number 5457715910. I realise that you might have a problem getting these exact products in Italy (although Wynnes is sold world wide), but if you look at the products on-line you will see what I am trying to describe. These modern dispensers make it much easier to evenly apply the sealant in a controlled manner. To secure the sump to the crankcase, I use 25mm long stainless cap-head (allen key) stainless bolts--they are 6mm bolts. If you have any problem getting the bolts, just let me know and I will get some for you.

 

[Richenrygarcia]

Thanks for the insight. May I play devil's advocate and ask why I need to stiffen the crankcase? I didn't know it needed stiffening.

I ask this because I've had my issues with gasket making putty being a messy undertaking when putting the components together and when taking them apart. If the gasket seals the oil pan thoroughly to the crankcase (i.e. no leaks) then what are the downfalls of using the fiber gasket versus a "liquid gasket"?

Not trying to instigate an argument here, I've just never read anything about the benefits of stiffening the crankcase.

Thank you all.

 

[Uaglio]

So is it safe to say the conclusions here are:

- don’t use a gasket if you want some additional crankcase rigidity, use RTV gasket maker and just bolt up the parts

- if you do use a gasket, use a rubberized one, not cork?

 

[Vitesse]

So is it safe to say the conclusions here are:

- don’t use a gasket if you want some additional crankcase rigidity, use RTV gasket maker and just bolt up the parts

- if you do use a gasket, use a rubberized one, not cork?

Aluminium to aluminium shouldn’t need a gasket or should I say it’s not recommended. A much better seal is achieved using a decent gasket sealant.

Myself and Peter (fiat500) both use permatex ultra grey which is the best RTV gasket maker I have come across and it’s a US product so should be easy for you to get your hands on. I used it on my alloy sump and no leaks.

https://www.permatex.com/products/g...igid-high-torque-rtv-silicone-gasket-maker-2/
Tony

 

[Toshi 975]

Thanks for the insight. May I play devil's advocate and ask why I need to stiffen the crankcase? I didn't know it needed stiffening.

The possible benefits of stiffening the crankcase become more important with tuned engines when things might stat flexing under load. It was recommended to me by a pal who has a 700cc engine he has developed and has shown over 100hp on a rolling road. Metal to metal joints with a sealant is far more in keeping with modern automotive practice. Not sure I like the sound of that red gasket paste, it sounds a bit like the old Red Hermatite which I definitely would not use. The tuned engine I have just finished rebuilding was put together in the mid 80s and the alloy sump had been fitted with a very thin paper gasket.
Most steel sumps when removed show some signs of deformation around the bolt holes where they have been over tightened , I would guess as an attempt to fix oil leaks. If this happened with an alloy sump fitted with a thick gasket them you run the risk of cracking the sump flange.
If your joints are "messy" after using "putty" then you may be using too much of the wrong stuff. I was born with two special applicators, one on each hand, they are called index fingers
After checking mating faces for any high spots and that they are clean I run a bead of sealant from a tube then use my finger to make sure I get coverage in the right areas.
My preference for fixing an alloy sump is to use stainless hex head screws with heavy duty rectangular section Spring washers as they spread the load better.

 

[Uaglio]

Thanks! Gonna use the Permatex Ultra Grey RTV. I’ve used it before and the gray color looks better on aluminum.

 

[the hobbler]

I agree with Dave (Toshi)---use stainless bolts ( I personally prefer 'cap-head' aka 'allen key' bolts)--25mm long, if I remember correctly, and the original factory rectangular washers. If you look at the factory washers they are very lightly 'bowed' with a light ridging on the 'up' side (which the head of the bolt goes against)---this way, when tightened down, they act as 'spring'washers.

 

[the hobbler]

Apologies for forgetting to add---if you would like to contact me direct ([email protected]) I will describe the 'Abarth' reccomended method for making the exhaust mounting brackets (on the side of the crankcase) more secure. It is not a difficult job, but the sump does have to be off to carry out the mod.