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.
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.
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
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.
First a mounting tool, than mounting a square piece of aluminium with the outer shapes of the part.
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!
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.
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.
do you have the part for sale
Dear Julian,
Unfortunately I sold all off them, I am planning to make new ones though, I will reply your comment if they are finished.
Best regards,
Matthijs
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
Hi, are you supplying these? I am in need of one ASAP please.
Best Regards
Graham
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.
Thanks Oscar!
Hi Matthijs,
For my 159 TBI I will also need to replace the variators and this oil pump seal.
Where can I get this upgraded one what is on the 1st picture? Is it worth to replace into that one?
Thank you.
Tamas
Dear Tamas,
Sorry for letting you wait so long, was busy, had Covid and was busy again, I still have some upgraded parts left, please send my a message through the contact form on my contact page and I might be able to help you.
Hello,
Thank you for all the info concerning the Delta. Recently I bought one and wanted to kindly ask you if you have additional advice concerning preventative maintenance. I already bought the seal you mentioned here and will be replacing it during the next oil change. Also i replaced one of the hoses for the oil vapor system as I noticed it cracked.
Could you also recommend a good service manual?
Thank you in advance!!
Hi Milan, there are a lot of discussions regarding this oilfeedpipe for the turbo. In the bolt there is a small filter that tends to block with dirt from the engine. The problem with these turbo engines that the turbo’s run a quiet high temperature if you compare it to diesel engines for example, this deteriorates the oil quickly especially when the wrong oil is used that can’t handle these high temperatures. So when oil is dirty because of deteriorated oil this small filter may clog up and causes the turbo to run on poor lubrication. My turbo expert told me to remove this filter, it only causes issues and does not add a lot of value.
Service manual is an issue, there is a really expansive option from Fiat with a 24 hour access pass (or an extremely expensive annual fee) bit there are also manuals available online for the 159 and 4C, send me an email and I can point me to the right direction. You can use the form on my contact page.
Bonjour,
J’aurais une question pour le remplacement du joint 71754365.
Le carter inférieur ce sors sans trop de complication ?
Pas besoin de sortir ma boîte de vitesse pour desserrer les vis de carter inférieur ?
Merci a vous !
Cordialement
Dear Sampol,
Unfortunately my French is very bad, could you write me the comment in English?
Regards,
Matthijs