Oil seal 71754365 1750tbi engine

There is a design flaw in the Alfa Romeo 1750 tbi engine and the Lancia 1.8DI engine. The issue is located in the design of the oil pickup tube attachment to the oil pump. A lot of issues are related to this leaky seal (71754365) for example, rattling camshaft phase adjusters, worn out turbo’s and excessive wear on cylindered components.

The issue is caused by the way this pick up tube is sealed to the oil pump. After a period of time the rubber of the seal (71754365 Alfa/Lancia and GM 55589549) hardens out and can start to leak as a result air wil be sucked op instead of oil.

Construction of oil pick up

I do understand the choices of the Alfa / Fiat engineers. As a cost and weight reduction the pick up tube is plastic instead of the more traditional metal ones. Mounting a plastic part in these severe internal engine conditions is a challenge. Mounting it the traditional way directly on the oil pump is a risk because it might snap of thus they choose to mount it very rigid on the oil pan.

An additional advantage is that the plates in the oil pan preventing the oil moving to the side can cover all of the oil pan. When doing sporty curves the plate prevents the oil moving to the opposite side of the pick up tube causing starvation of oil supply. The way the pick-up tube is mounted there is no need for a big cutout for the pick-up tube.

Unfortunately the engineers did not spend much time on the oil seal. An attribute of rubber materials in hot oily conditions is it can harden out. Especially if you try to cover a 4.5 mm distance.

Oil seal 71754365 causing issues!
Oil seal 71754365 causing issues!

Also issues at GM / Opel / Saab

The same part is used in several GM diesel models. Back in the day the Fiat group worked together with GM sharing platforms and technology, that did not last long. Funny its now the same company; Stellantis. I did even found a petition regarding this issue begging for a warranty repair.

Oil seal
source: Reddit
Oil seal 71754365 causing issues!
Oil seal 71754365 causing issues!

Can i fix it?

The image above is an oil pan and an oil pump of en seized Alfa Romeo Giulietta engine I bought on our local Ebay. Although there is a solution available on Ebay from a guy who makes round aluminium parts with oil seals you mount instead of the original one I was not willing to compromise the internal diameter of the upgraded seal so I made another design. The pump is high volume and a restriction like the round seal replacing solution might influence the performance.

The Design

Oil seal upgrade 71754365 design top
Oil seal upgrade 71754365 design top
Oil seal upgrade 71754365 design
Oil seal upgrade 71754365 design

I made one myself as a proof of concept. I will not use it in the Lancia because O-ring tolerances are quite strict and I do not have the proper tools to produce it. Nevertheless, I made it anyway just to see if it wil work out and I like turning on the lathe.

Tool for Oil seal upgrade
Tool for Oil seal upgrade

First a mounting tool, than mounting a square piece of aluminium with the outer shapes of the part.

Tool for Oil seal upgrade with part attached
Tool for Oil seal upgrade with part attached
Oil seal upgrade mounted on oil pickup
Oil seal upgrade mounted on oil pickup
Oil seal upgrade 71754365 mounted
Tool for Oil seal upgrade 71754365 with part attached

As O-ring material I choose Viton purchased from the company Eriks. Viton has a high resistance to heat and chemicals like engine oil. Eriks provides an O-ring calculator which I commonly use for O-ring calculations.

At this very moment I am having the parts machined, off course one for the Delta but I will get some additional ones. If you need one yourselves send me a message!

7 thoughts on “Oil seal 71754365 1750tbi engine

  1. Hi there and thank you for time writing this very informative article!

    I have one question; can rubber seal be related with delayed oil lamp switching off? During cold start engine is fired up and oil control lamp switches off 2 seconds later, there are no faults displayed for poor oil pressure. During those two seconds phase variator also rattles.

    1. Hi Lakijanovic,

      That could definitely be the case. Whit what I know now I would not drive an inch and replace the seal. If you can do it yourselves its only like 10 euros if you get it from autodoc or 20 if you get it OEM. You will probably spend an extra 100 euros for new oil and filters but I can tell you from my own experience that replacing stuff like turbo’s and camshafts is a bit more expensive. I don’t know what it will cost if you let a mechanic do the job but it should me no more than 3 hour job for an experienced mechanic.

      I took the time to clean the oil pan thorough, If you want to remove the brown sludge you can use oven cleaner, you know… the foam stuff what will make you cough if you inhale it.

  2. Wow, thank you for this fast response! I’ll do it by my own, and yes; I often use that cough kitchen stuff (Axel Saggrasso or something) for cleaning..
    Is there any difference in quality of those oem or replacement seals? I’ve found only some “Elring” brand and it’s a bit under 10 euro..?

    Yesterday I’ve changed only engine oil and filter, I’ll check oil lamp later.

    Thank you again and I’ll keep updating here

  3. Thank you very much for your GREAT content Matthijs!
    I own a 159 SW 1750 TBi and will probably ask my mechanic to replace this rubber seal next time I bring him my car.

Leave a Reply

Your email address will not be published. Required fields are marked *