Throttle body heater hose delete

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Lock
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Throttle body heater hose delete

Post by Lock » Thu Aug 22, 2019 11:36 pm

Bear with me here.

Underneath the manifold is a metal pipe, one end has a hose that goes to the pump/thermostat area, the other end to the coolant tank and cabin heater.

I want to remove this now rusty pipe and use the all-rubber hose equivalent from the e34 535i. It's pretty close, will need to cut a little and get an adapter to link up to the coolant tank.

However, there is another set of small hoses that go from the metal pipe up to the throttle body for heating(PCV valve opening?), then down to the idle speed control (Jules Verne device) and into the block near the starter motor. I know the throttle body heater isn't really needed except for snow, and I'd getting rid of the idle speed control and moving the temp sensor up to the outlet assembly. So this small pipe isn't needed for my application.

My question is though, can I just plug the block where this hose came out of - or is this small hose required for coolant flow? It wasn't an afterthought so I don't want to block off a small but possibly critical part of engine cooling. I am sure I read somewhere once someone saying "do not block this line", but I can't find it again. I can plumb it back in to the coolant tank adapter if it's needed but it would be neater to block it off.

Obviously the M30B35 doesn't have this, nor does it have an opening in the back of the head for the gooseneck heater, but it was designed that way and may have different coolant flow paths.

Does anyone know if this little hose is important?
1979 528i 5-speed conversion G260/6
1980 Honda CX-500

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Re: Throttle body heater hose delete

Post by PatinaBeforePolish » Fri Aug 23, 2019 8:00 am

Lock,

Yes, that metal pipe is NLA and I was also thinking of alternatives. Luckily mine was only slightly corroded on the ends so I had it zinc plated and so far so good, but it's good to know there's a close alternative - nice sleuthing! Are you referencing e34 part number 11531711002?

I think the feeder from the pipe to throttle body to the Jules Verne device continues on to the block only to provide a coolant flow path. I don't think it would be an issue to eliminate that flow as coolant continues to circulate from the block to the expansion tank. But one of the sensors (the one facing downward) on the JV device sends a signal to the cold start valve correct? Where/how would you re-locate it? Also, do you need to block the feed at the throttle body heater?
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Mike W.
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Re: Throttle body heater hose delete

Post by Mike W. » Fri Aug 23, 2019 11:43 am

B34s don't even have it, hell, 82 B32s don't either. As long as you don't need that hot coolant for the sensors down there, sure, you can block it off. It's even bolt size and threads in the block not some metric tapered pipe.
Mike W.



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Re: Throttle body heater hose delete

Post by Lock » Fri Aug 23, 2019 11:56 am

Yes, e34 part 11531711002 is exactly the piece. I have an e34 parts car (I was going to put the engine in my e12, but the iron block is cracked so it's toast). So I've been seeing what will transfer across. That hose is almost perfect - it lines up with both the water pump side and the cabin heater as those pipes are in the same place. BMW only changes things slowly it seems.

However two issues, 1. the coolant tank is top center on e34, ours is off-set but by cutting, slightly bending and a male-to-male adapter would allow this to work. 2. That small hose doesn't have anywhere to go - however all of the male to male adapters I see have a threaded hole as they're designed for a gauge or sensor. So for your setup you could thread in a hose nipple and could route the hose back to that connection.

There are two sensors in the Jules Verne device you're right - the ECU temperature sensor, and the cold start injector. You could move both of those up to the outlet block by the water pump. And then if you had a 1980+ electric idle speed controller (or bought one and linked it to the fuel pump power line), you wouldn't need any of that piping down there and could remove it entirely.

For my car, my L-jet system failed so I am installing the e34's Motronic 1.3 system in so I don't need any of these connections (will make a build thread once I make some progress if folks are interested).

Mike - thanks for confirming. I was happy to thread it shut with a bolt but wondered if it served any other heat release purpose besides those two devices.
Last edited by Lock on Fri Aug 23, 2019 12:09 pm, edited 1 time in total.
1979 528i 5-speed conversion G260/6
1980 Honda CX-500

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Re: Throttle body heater hose delete

Post by Lock » Fri Aug 23, 2019 12:02 pm

PatinaBeforePolish wrote:
Fri Aug 23, 2019 8:00 am
Lock,

Yes, that metal pipe is NLA and I was also thinking of alternatives. Luckily mine was only slightly corroded on the ends so I had it zinc plated and so far so good, but it's good to know there's a close alternative - nice sleuthing! Are you referencing e34 part number 11531711002?

I think the feeder from the pipe to throttle body to the Jules Verne device continues on to the block only to provide a coolant flow path. I don't think it would be an issue to eliminate that flow as coolant continues to circulate from the block to the expansion tank. But one of the sensors (the one facing downward) on the JV device sends a signal to the cold start valve correct? Where/how would you re-locate it? Also, do you need to block the feed at the throttle body heater?
Re the throttle heater - I've read people blocking this off with no issues. I assume it heats the throttle for below freezing conditions (the Alps?) and also seems like a hangover from carburetors as it's not present on later engines. It's also right next to the PCV valve which makes me think there might be a wax pellet in there that opens that when the car is warm?
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Re: Throttle body heater hose delete

Post by 528i-1981 » Sat Aug 24, 2019 5:16 am

Lock, you should consider building a gallery on the Motronic conversion, something like Dave (maybeillbuyit) did with his rehab.
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Re: Throttle body heater hose delete

Post by Lock » Sat Aug 24, 2019 4:11 pm

Will do, I'm still dissembling and comparing parts. I have a pros and cons list of log manifold vs e34 manifold, because they seem about 50/50 in terms of difficulty. Firstly I want to see if the e34 manifold will even fit - suspect it will hit the brake booster.

On the upside, I've confirmed what Mike said in another post that the Motronic injectors will fit on the log manifold, but I'll see this weekend what the realistic options are.

Was hoping to drive it this summer, but looks like that's out. Maybe in the fall..
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Re: Throttle body heater hose delete

Post by Lock » Sun Aug 25, 2019 11:15 pm

In my RealOEM searches I also found a more viable setup for e12s - the later e28 535i layout, with hose and plastic T piece;

11531274210
11531272866

They might be more appropriate for stock setups. Again for me I'm removing that small hose set entirely, but if someone could find a way to tap into it with a small connector, that would be a good replacement for stock e12s to remove the steel pipe. Maybe cutting that hose in half and adding another adapter in the middle where the original pipe connects. The coolant pipe is offset, so might need to two cuts.

For my setup, I'm probably going to use the e34 coolant pipe adapter unit (because the ECU coolant temp sensor doesn't fit - I could keep the OEM unit and use a thread insert, deciding) and put the sensors in it, and put a bolt in the threaded block hole to plug it. Those hoses are hard to get to by the side of the road so it's worth ensuring they're healthy.

When I took the rubber hoses off the steep pipe, it was starting to rust and disintegrate at both ends. I keep on top of my coolant changes and so did the PO, so I think after 40 years it just eventually falls apart.
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1980 Honda CX-500

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Re: Throttle body heater hose delete

Post by 528i-1981 » Mon Aug 26, 2019 6:09 pm

How many miles on your M30, Lock? The disintegration is probably more of an age thing, but I _think_ a higher-mileage car, where the coolant and it's anti-corrosive payload is circulating more frequently, might fare a little better if the coolant was religiously changed. I worry about mine now. Ah screw it, the thing is a rolling time bomb in one way or another.
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Re: Throttle body heater hose delete

Post by Lock » Tue Aug 27, 2019 3:30 pm

When I bought mine, the clock had stopped at 114,000miles so hard to say. It has a AMC head installed "recently" so the original head cracked at some point. It does appear to have been reasonably well maintained throughout its life though, and not driven a huge amount.
The corrosion in the pipe wasn't meant to scare anyone. I just noticed the end was jagged but there was ample surface to maintain a seal, and there seem to better options to replace it entirely (from both e28 and e34 parts).
If it's any consolation, I can say that most of those hoses appear to be original, or at least many years old, but still with enough life to maintain pressure.
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Re: Throttle body heater hose delete

Post by Lock » Fri Aug 30, 2019 11:11 pm

I did a side by side comparison and took some photos. I will try bending the e34 reservoir hose around, it's very flexible, and link it up with an adapter to the oem reservoir hose.

Image

Image

Image

This is the bolt size I used to seal up the block hole

Image
1979 528i 5-speed conversion G260/6
1980 Honda CX-500

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