Intake Manifold E34 535i

[Rek]

I decided to replace the manifold to idle control valve hose in a search for an air leak affecting my engine. I also thought that I could replace the injector O rings too.

The injectors had to be prised out with a screwdriver and were in a real state with broken bits. There did not seem much trace of the plastic ends of the injectors in the manifold. One seemed jammed open, another wasn't in fully and all the lower O rings were hard.

The history behind the engine was that it was from a B10 Alpina which had done 300,000 miles. The engine had been rebuilt (at a cost of £12,000 as per the invoive) at 225,000 miles. They had obviously not touched the injectors.

Because the injectors had fractured, I took the manifold off, finding that the lower bolts were only hand tight at best. There was evidence of leaking fuel on the lower connecting face of the manifold.

New/remanufactured injectors on order.

I have a question though. Under the manifold are two small pipes which allow air into the manifold. Nothing was connected to them but suspect they might be something to do with the evap valve from the fuel tank or carbon canister on the original donor car. I did not fit the engine myself.

These are marked in red on the attached photograph (not my manifold - mine does not have the evap valve).

Can I just block these off to retain the vacuum? Anyone know what they were for? Perhaps I am missing some vacuum lines.

 

[arnie]

Hi Rek,

since you don't really need that many vacuum lines to trigger something on Motronic engines, I'd close these pipes. The only necessary vacuum hose I know, is the one for the fuel pressure regulator.

If this would be my engine (B10 is really great stuff), I'd swap the intake manifold to the old style. Looks way better inside the engine bay, if you ask me ....

Greets

Ingo

PS: If you'd need a good source for injectors, there's a really nice guy, offering refurbished and volume balanced sets for really reasonable prices. I dealt with him already for a couple of sets in the past. Really quick service and perfect injectors. I could send you the contact information if you like.

 

[Rek]

Hi Rek,

since you don't really need that many vacuum lines to trigger something on Motronic engines, I'd close these pipes. The only necessary vacuum hose I know, is the one for the fuel pressure regulator.

If this would be my engine (B10 is really great stuff), I'd swap the intake manifold to the old style. Looks way better inside the engine bay, if you ask me ....

Greets

Ingo

PS: If you'd need a good source for injectors, there's a really nice guy, offering refurbished and volume balanced sets for really reasonable prices. I dealt with him already for a couple of sets in the past. Really quick service and perfect injectors. I could send you the contact information if you like.

Thanks for this Ingo. Even with the ailments I mention, the engine pulled very strongly, so I can only imagine how it will go once righted.

I will plug the pipes. I will consider the older intake manifold, but I am wary of affecting the performance. Are you referring to the one that looks like a bunch of bananas?

 

[arnie]

Hi Rek,

a bunch of bananas, right, like the csi genuine engine had them. It might cost a bit of performance, but I suppose you won't recognize that at all.



This is how it looks in my car. You see it was the Motronic version, before I did some certain mods.
Most significant difference is the ECU system (Ecumaster Emu) and the old style intake manifold. injectors looking similar as yours, airfilter box is genuine csi, so that the overall look comes close to the csi engine.
As you maybe can see I only have 2 vacuum hoses attached to the intake manifold. One is for the fuel pressure regulator and the other is feeding the map sensor for the ECU. Nothing else necessary here.

Greets

Ingo

 

[Rek]

Does anyone know what they would have for in the original E34?

Just curious.

 

[Drew20]

I'd keep the B10's manifold, yes the bananas do look better but it's a B10 Alpina hand built engine. Ok so it's done some miles and had a dubious rebuild, but it has provenance!!

254 bhp as per spec (or 360 bhp if it's the biturbo, woohoo!)

Can't help with the vac ports, no need for dizzy advance, can't think what they'd be for. They may have been capped off on the B10 of course. I can recommend the alpine register forum as a great font of knowledge
http://thealpinaregister.com/forums/

 

[Rek]

On reflection I will keep the Predator manifold. A compression check on the engine found that it had 200psi or thereabouts on each cylinder. I think thats about 10 psi down on where it should be so I am not too concerned about the engine.
I found the result for the pipes on Bimmerforums.co.uk or at least one that makes sense.

It is on the hand drawn image attached.

 

[Markos]

Forgive my ignorance but what makes the b10 manifold any different from a standard b34 manifold? The b10 turbo manifold was modified, placing the TB on the opposite side. This one looks like a stock BMW manifold.

Do what you wish but an early manifold with e21 bananas seems like a good period correct option to me.

 

[Craig Bower]

Rek,
I have an first series Moronic 1.0 e12 base car that is quite original. On it, one of the ports goes directly to the fuel pressure regulator. The other port goes to a tee that splits between the PCV port and the vapor canister. Hope this helps.
cb

 

[Rek]

No difference in the manifold AFAIK.
I was looking for a solution to a problem and gave the donor car in case that made a difference to the solution.

 

[Rek]

Rek,
I have an first series Moronic 1.0 e12 base car that is quite original. On it, one of the ports goes directly to the fuel pressure regulator. The other port goes to a tee that splits between the PCV port and the vapor canister. Hope this helps.
cb

I know its a typo but I like the idea of Moronic fuel injection system. It certainly sums up my attempts at working it out.

 

[Craig Bower]

Auto spellcheck is really frustrating sometimes, but without it you likely wouldn’t be able to understand anything I am trying to get across.

So far, I have been presently surprised at how well even the most rudimentary version of Motronic functions on our engines.

 

[Drew20]

No difference in the manifold AFAIK.
I was looking for a solution to a problem and gave the donor car in case that made a difference to the solution.

I think it's relevant to know. Personally I'd be a lot more respectful of an Alpina lump (being rare, tuned and hand built) than a boggo M30

Sound like you also got a useful answer from Craig, to go with the unsolicited advice from me!