Simon's take on: 'Mess Under the Intake'

[roguetoaster]

Yes, this cleans up the under intake area, making it less prone to failures/leaks in future. On my previous 318 I did the conversion, on my current on I left it alone as everything is in good shape.

[Roysneon]

So the main point of taking this stuff out and bypassing everything is to reduce failure points? I got my engine from a parts car that ran 'as far as I know'. I'm leaning toward leaving it all alone as long as the hoses look to be in good condition.

Basically, I understand what you're doing, I just need clarification as to why this is such a common procedure.

[Chuck C]

wouldn't it be better to replace those components instead of putting a Band-Aid on them?

[Chuck C]

The only purpose of the bypass valve installed during the coolant system recall campaign is to cut off flow of coolant to the heater core in case of elevated coolant temperature--period. When the coolant reaches a certain temp, the valve closes, and when the coolant temp drops to a certain point, the valve opens (maybe); there is no halfway operation. This recall was designed to shield BMW from lawsuits over ruptured heater cores. If a car has compromised components in the cooling system

[Simon S]

Someone asked about the bypass and how it works- it is actually a second thermostat. When the coolant is cold, it allows everything to flow. When it gets hot and the pressure rises, and the solenoid controlling flow into the heater core is shut, this thermostat opens and allows coolant to flow around the heater core, thus bypassing it and reducing pressure on that solenoid, whose manifold is the part that is known to fail. the bypass causes a *slight* decrease in heating capacity but I doubt you'd be able to tell the difference. The coolant will still flow through the path of least resistance, and when the solenoid on the core is open, it's flow volume is an order of magnitude larger than the bypass.

Excellent! Thank you for sharing this knowledge. Greatly appreciated.

[gearheadE30]

Someone asked about the bypass and how it works- it is actually a second thermostat. When the coolant is cold, it allows everything to flow. When it gets hot and the pressure rises, and the solenoid controlling flow into the heater core is shut, this thermostat opens and allows coolant to flow around the heater core, thus bypassing it and reducing pressure on that solenoid, whose manifold is the part that is known to fail. the bypass causes a *slight* decrease in heating capacity but I doubt you'd be able to tell the difference. The coolant will still flow through the path of least resistance, and when the solenoid on the core is open, it's flow volume is an order of magnitude larger than the bypass.

as for the leak to the back of the block, if your bypass from the black plastic tube to the side of the head is leaking, the castings on the block will make the coolant flow to the rear. Mine did this. Also, head gaskets can leak coolant, so I'd check that. There is also a coolant port on the back of the head iirc; it goes to the heater. That said, I might be confusing it with an M20. Also check that your coolant block drain is tight (19mm bolt on the side of the block, under the exhaust manifold).

[Simon S]

Cool.
Thanks.
You're welcome.
Glad to be of help.

[TimKninja]

BUMP. This is the most useful thread on the M42 Forum, and Ill b e using it a lot next weekend, thanks Simon!!!!

[trigtm]

A note on bleeding. I think the main problem is that the reservoir is not thr highest point in the system as with most cars. If you have the car on an incline for final bleeding, it will help alot.

I've been bleeding my car several tiems now and have had an issue to get it to take mroe coolant. Once I completly topped off the reservoir, it seems to be at the right level but the heat is only barely warm so I'm sure I have more bleeding to do.

[freeride53]

Great thread Simon, I'm about to tackle this over my break in the next few weeks!

[spanish pants]

There´s a little purple question mark on the throttle body diagram. What does this get plugged with?
The throttle body on mine is plugged with a little rubber cap that is currently held together with electrical tape. I´ve looked on real oem for what originally goes there but with no luck.
Anyone know?

[lgb240]

I deleted the hoses going to the heater plate, but I left it in there. I can't see how it would freeze if it doesn't have any liquid in there, just air. I've had no problems since I did the mess under the intake.

One thing you have to rememeber though is to bleed the system really well or you will overheat. That's why i did and had to go back and bleed it 3 times.

Thanks for the input. I don't think it's the liquid in the plate that would freeze (it's antifreeze) I'm guessing that it would keep moisture in the air going through the intake from freezing in the intake plenum.

I hear you on the bleeding - what a royal PITA these cars are to bleed. Someone at BMW should have had their peter slammed in the door for coming up with such a sh1tty system that does such a great job of trapping air.

[Dj Buttchug]

wait a minute wtf is up with coolant leaking in above picture. as far as i know there are no coolant lines or heater core anything that far back.

[shEck3lls0]

I deleted the hoses going to the heater plate, but I left it in there. I can't see how it would freeze if it doesn't have any liquid in there, just air. I've had no problems since I did the mess under the intake.

One thing you have to rememeber though is to bleed the system really well or you will overheat. That's why i did and had to go back and bleed it 3 times.

[lgb240]

Nice write up ...

I've been fighting the 'mess' under the intake for a few days now ... I've replaced all of the hoses that carry coolant, but, there's still a leak under the intake. I suspect is coming from somewhere around the TB heater crap.

Question ...

Has anyone done the TB heater delete set up that runs their car in a winter climate? Has there been any issues with the TB freezing up?

I'd like to eliminate the TB heater and perhaps the source of the leak, but am worried about winter drivability. My 318is is basically my winter car.

Any help would be appreciated.