Heater core delete coolant hose routing

[99MPower]

So, after some technical discussions with some very knowledgeable people in the Chicago area, we are at a cross roads and looking for some input from some other people.

After most people delete the heater core, everyone just puts in the M50 block off plate, and plugs the return from the heater core hose off the end of the hard coolant line on OBDII cars.

From my research, people who leave the coolant adapter on the back of the head, and just connect to the back of the hard coolant line, have had issues with cooling the cylinder head, as the coolant essentially just circles in the cylinder head without being forced through the radiator.

In the "normal" way people do it, you have blocked off any coolant flow through the back of the cylinder head. What I would like to do, or attempt to do, is route a line from the back of the cylinder head to the return side of the radiator, and force the coolant back through the system. Essentially welding an AN fitting on the return side of radiator and forcing coolant back in the system.

What side of the radiator is the "return" side, and what side is the "feed"?

diagram of the cooling system for reference

[thejlevie]

Seems to me that runs the risk of overheating the head by diverting part of the flow within the head. I think the best thing to do is simply to plug both ends of the heater loop.

If you've never driven on track in moderate to heavy rain, you may find later that retaining the heater just for the defroster would have been a really good idea.

[99MPower]

Jim, the "standard" that most people do is to plug the rear of the cylinder head. That is not uncommon, and works for most people.

What I want to do is guarantee that the loop is retained, and coolant from the back of the cylinder head is able to be cycled back into the coolant system/radiator.

The heater core was removed for a reason, and will be replaced with a small 3"-4" marine electric fan, to maintain air flow over the windshield like u described for cold mornings/rain/etc....

[thejlevie]

I'm well aware of what the standard is. Plugging the heater loop is the right way to eliminate the heater.

My argument against what you propose is based on the flow of coolant through the engine. I don't have any reference material here with me, but from memory coolant goes from the pump, through the block, up into the head, and then through the head to the thermostat and out to the radiator. If you take coolant off the back of the head and to the radiator you've reduced total flow through the head.

[99MPower]

hmm... interesting... do u know where u got that information?

when the heater core is in the loop, the coolant runs out the back of the head, so I dont think the total flow would be an issue, as you've just replaced the heater core loop, by going straight to the radiator

My buddy and I were trying to diagram everything out. He has dual temp guages in his S54 swapped E36. One in front and one in rear, and has seen as much as 30 temp difference between the two. Thus the reason for all this. If motor is running optimally around 200-205 at temp sensor in head (old TB coolant barb), then the back of the head could realistically be up in the 220-230 (BAD).

I know the S54 and S52 are different, but come from the same basic principles. Thus the reason for wanting to make sure I got good flow through the ENTIRE cylinder head.

Everything is still taken apart from heater core removal, I have all my gauges on the way with ODB, and just trying to get everything squared away before the season starts

[Michael9218]

You're mistaken on the flow from the back of the head. This is merely a takeoff for flow to the heater core, which when shut off has no flow. The proper flow is in the head and not out the back. I'll stress again that the port at the back of the head is not in the flow loop. It is an alternate routing of some of the head coolant to the heater core...plug it.

[99MPower]

You're mistaken on the flow from the back of the head. This is merely a takeoff for flow to the heater core, which when shut off has no flow. The proper flow is in the head and not out the back. I'll stress again that the port at the back of the head is not in the flow loop. It is an alternate routing of some of the head coolant to the heater core...plug it.

point taken...

as a data point, I spent the $30 for a 90 degree NPT fitting, and another autometer temp sender. I will be taping the plate, and running a 3 pole switch so I can occasionally check the coolant temp in the rear of the cylinder head if I want.

After seeing the 30 degree temp difference from front to rear on the S54 cylinder head, I want to see what kind of differences there are on the s52. If there is a problem, then I will go from there when that problem arises, but for now, it will only be used as a monitoring/data source

[94is]

I have a "T" installed under my intake manifold. One end of the T goes to the back of the waterpump, one to the back of the head, and the other goes to the bottom of my aluminum expansion tank. Been running it like that since last June without a single issue.

[Michael9218]

That will work as it replicates the flow with the heater turned on and water is returning to the radiator. It is unnecessary complexity, though. You don't need that hose coming from the back of the head and you're taking some water out of the head that hasn't completed it's routing through the head.

[94is]

Yeah, when I plumbed it I wasn't sure if I needed it or not so I worked it into the equation. Maybe next time I have the intake manifold off I'll change it up. For now it will stay.

[OppLock1]

You're mistaken on the flow from the back of the head. This is merely a takeoff for flow to the heater core, which when shut off has no flow. The proper flow is in the head and not out the back. I'll stress again that the port at the back of the head is not in the flow loop. It is an alternate routing of some of the head coolant to the heater core...plug it.

I believe this is what actuates the flow to the heater core??



(taken from another forum member, routing was incorrect in the pic)

For a cleaner set up, I believe BW sells a hose kit that eliminates the hoses that run to the TB and heater core outlet.

http://store.bimmerworld.com/coolant-hose-kit-p168.aspx

[99MPower]

that kit is to replace the OEM hoses... I want to get rid of all of them

[jcrist]

Plug them. No water runs off of mine, all holes plugged by BW

[M3 Euro LTW]

You don't need that hose coming from the back of the head and you're taking some water out of the head that hasn't completed it's routing through the head.

Really now? Water runs from front of the engine to the back. Do you have data to support that there isn't some level of stagnation or super hot coolant at the back of the cylinder head whereby getting even more water out the back, even if it's mixed in and re-used doesn't decrease the temperature gradient from front to back on the head?

PTG did this, and I know that doesn't mean that it is automatically the best or right for the M50 engines.....But they sure analyses the heck put of the question. I'll try to post a link showing just this concept.

http://www.kwyjibo.com/ispeed/ptg2k/...tm?ptg2k27.jpg

See? Pretty clear on that image with the SS line and aeroquip terminations.

(Not that it proves my point, but I'd love to see someones DA showing otherwise, realize I'm out on a limb here)

[M3 Euro LTW]

I am trying to figure out the best way to delete the heater core and have the same thoughts... I don't like capping it in case some coolant flow down the heater core path is beneficial.

Maybe the best way to play it safe is to use a step down in hose size for the return on the heater core bypass, that way you avoid coolant stagnation in the rear corner(if it exists), and most of the flow will follow the path intended.

http://www.kwyjibo.com/ispeed/ptg2k/...tm?ptg2k27.jpg

This is a better view from the same website.

The S54 has a slightly different coolant return manifold than either the S50BX engines, and especially the M5X engines.

It more closely mimics the S14 and S38's where they had a manifold too, but on the exhaust side. In these cases, pairs of cylinders each have an exit right out of the head, to join the others and return to the thermostat assembly.

On the S50B3X, the manifold forces the coolant to travel internally in the head towards the front between 1 & 2, where it exits, and then goes to thermostat.

http://www.realoem.com/bmw/showparts...11&hg=11&fg=15 (PTG image engine)

S54: http://www.realoem.com/bmw/showparts...11&hg=11&fg=35

Part #7 here has three entries from the cylinder head to gather the return coolant. Venting even more out the back is slightly different than in the S50 or M50 where the return has to be IN the cylinder head to get back up front.

I'm still curious as to whether any one has data logged whether drawing additional coolant off the back, and returning in direct, not through the heater core helps balance the engine's temperature gradient from front to rear. I think it might.

Getting heat out of the cylinder head to make more power as well as prevent hot spots is important enough that some big turbo projects actually re-route the coolant pathways...cylinder head first, then down to the block, as well as changing entry and exit pathways from the head.

Maybe no one is posting because its boring, or they're pissed that speed and longevity secrets are being discussed in open, or no one has real data one way or the other?

[ETM]

The OP is asking about an M50 based engine. While the heater supply port is located at the back of the head it is the end of a galley that draws from the center of the head. Drawing water from the heater port is not likely to reduce temps at the back of the head.

Coolant flow is controlled by the HG. Most of the water holes are about 5mm. Some of the holes at the rear are 10+mm. The sizes are intentional in order to even up the temps across the engine.

[99MPower]

this is for m/s 50/52 motors..

the s54 is COMPLETELY different

[Greg S]

HG is head gasket. The holes in the head gasket are different sizes than the water ports, this controls the flow.

[M3 Euro LTW]

Mario adds details I did not know about the M50 that change my opinion to some extent, but not completely either.

Given that I assume he's correct, and that the galley that feeds the rear exit for the coolant to go to the heater core is internally drawing from the MIDDLE of the cylinder head, then it doesn't preferentially drain off the back.

The whole idea that maybe the back end of the cylinderhead might benefit from better cooling won't apply in this case like the S54 or S50B3X.

(so I was wrong about this)

What still remains to be documented however, is whether or not there may not still be some benefit to drawing more coolant out of the head through that exit than blocking it.

I grant it doesn't seem like it will preferentially cool the back, but overall, if done properly, it might be a cool tuning trick to improve longevity, decrease overheating, and allow more power with cooler temperatures.

I'll pick this up in private with Calvin, talk to him all the time... it IS an interesting subject.

[99MPower]

Unfortunately, after ordering the extra sender, and NPT fitting, the probe sender wont fit in the 90 degree elbow, and its not the proper sender for the guage I bought.

I will be getting around to getting the correct parts later on, and WILL be doing a second water temp gauge, just not immediately.

[ETM]

While I'm skeptical of there being any benefit to pulling the water from the port on the back of the head, that in itself is not the issue I see. It is that in the most common version of this mod people route the water back into the system thru the return behind the water pump. At that entry point the hot water re-enters the engine again without passing thru the radiator. I prefer to keep it simple and just block off the back of the head. I do know one builder who attaches to a 'T' fitting the upper radiator hose which is also kosher.

[badmonkey]

While I'm skeptical of there being any benefit to pulling the water from the port on the back of the head, that in itself is not the issue I see. It is that in the most common version of this mod people route the water back into the system thru the return behind the water pump. At that entry point the hot water re-enters the engine again without passing thru the radiator. I prefer to keep it simple and just block off the back of the head. I do know one builder who attaches to a 'T' fitting the upper radiator hose which is also kosher.

I had nothing but problems when plumbing the rear port back into the
system. After blocking blocking off that port, no cooling issues.

[skippystahl]

I have found three different threads on this subject and am satisfied that blocking off the back of the head and plugging the back of the water pump is just fine if not the better way to go. If this is done though there is still the feed line from the reservoir that no one has mentioned. Since you can't remove the reservoir due to the filler cap, what is everyone doing about this extra hose. Are they plugging this as well or is it necessary to buy a new radiator?

[KnudsonsM3]

why is Calvin banned?

[99MPower]

why is Calvin banned?

I'm not