Induction Manifold
 

The car is an 1800E with the D Jetronic. The car wasn't idling very well so I have gone through the process of checking the idle adjustment (throttle stop screw & throttle position sensor) which were all fine. I also clamped off the auxiliary air valve plus checked for a vacuum on the brake booster. However, I find that I can still screw the idle adjustment screw all the way in and the car still runs.

I therefore put a smoke generator on the induction manifold to see if there were any air leaks and found smoke was coming out of the steel blanking plug on the rear end (nearest the bulkhead (firewall). If I run the engine and put my hand over the blanking plug I can feel a suction.

Is there meant to be a sealing washer or O ring to seal off this blanking plate or am I going to have to wipe some JB Weld (or similar) round it to seal it off?

Ace;

I expect your finding is a somewhat unusual occurrence ...but it would definitely contribute to idle issues in the D-Jet...and compliments on your technique for locating it!

The (est.) 2" Blanking Plug is set into the alu Intake Man at time of manufacture, similarly to an expansion ("freeze") plug in the engine (center displacement of the dome form, to expand sealing surface)...if it was replaced, and not properly installed at that time, or if it has simply developed a leak due to galvanic corrosion of the dissimilar metals, I would first check to see if the installation looks normal and proper, and if it does look OK, and the leak is around the edge, almost any fuel compatible sealer from gasket gook to RTV, to JBW will do the job until next time Intake Man is off, and access is good for a proper repair (removal and resetting with sealer!)

If you want to remove the BP with Intake Man in place, I should think that by removing the fresh air snorkel and opening the throttle, a broomstick or similar can be used to impart impacts to the back of blanking plug to "undome" it and persuade it out of position to allow removal...a simple cleanup of surfaces and reinstallation and resetting (with sealer!) will then give a permanent repair.

Good Hunting, please let us know how you make out.

Hi Ron,

Thank you for your reply to my query. I have put a wipe of JB Weld around the edge of the steel plate. I did this while the engine was running on the basis the manifold vacuum would suck the JBW into the gap.

It seems to have worked, with the engine running I cannot feel any suction and the idle seems to have stabilised.

Thanks

Andy

Andy;

Thanks for follow-up!

I am currently in contact with another 1800E owner...helping him to understand and troubleshoot engine running issues...when I mentioned the importance of not having false air entering by way of hoses or components, I happened to also recall your recent finding, and related it to him...he subsequently checked, and sure enough confirmed a similar leak...an interesting fact is that he is in Hawaii, with no lack of nice weather, but also plenty of corrosive ocean air! ...so I must ask: Is Romford near the ocean?

I thought yours was an unusual and interesting finding, but twice in a month!?!...I guess its maybe not so unusual, after the construction is 50 years old, and it shows that the effect Luigi Galvani discovered in the 1700s is having its way with our cars to this day.

Cheers