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**Brian D** · 08-19-2010, 02:16 PM

Originally posted by Erick View Post

. It warms up to 175deg F, and after a while the temperature starts to climb (about 2-3deg/min) on a hot FL summer day. It'll keep creeping it up all the way to 190 where the water starts to boil and I shut the car off.

First off, how are you getting those temps? A lot of cars run 190 degrees, and water shouldn't boil at 190.

**Erik j** · 08-19-2010, 02:19 PM

Put coolant in it, not straight water.

**slammin.e28** · 08-19-2010, 02:25 PM

Originally posted by Erik j View Post

Put coolant in it, not straight water.

^^True that!

**Erick** · 08-19-2010, 04:51 PM

Originally posted by Brian D View Post

First off, how are you getting those temps? A lot of cars run 190 degrees, and water shouldn't boil at 190.

I have a mechanical temp gauge hooked up to the thermostat. I also kept the original electrical temp gauge from the coolant hooked up just for sh*ts and giggles.

But regardless of whether the gauge is accurate or not, the water is still boiling. Therefore, I'm open to suggestions as to how to fix the overheating first, then deal with possibly inaccurate gauges.

Originally posted by Erik j View Post

Put coolant in it, not straight water.

Says who? I don't mean to be rude, but most cars I see on the track are running pure water. Actually, I've seen tracks forbid the use of anti-freeze on their cars.

**george graves** · 08-19-2010, 04:57 PM

^well anti-freeze does a lot more than just for winter time driving. It's keeps your head and block from becoming a battery and eating away at the metal (but I bet you knew that)

First thing is - I think water runs through our heater cores none-stop. Where you have the hvac set to heat or not. I think it keeps corrosion down that way - so that all summer long you don't have stagnate water in the core.

Secondly - Are you sure the water passages on the back of the block are just for the heater? I'd look there. I love your "get 'er done" attitude, but did you not look into that before blocking it off? I assume you must have. What did you find?

**Erick** · 08-19-2010, 05:04 PM

Originally posted by george graves View Post

First thing is - I think water runs through our heater cores none-stop. Where you have the hvac set to heat or not. I think it keeps corrosion down that way - so that all summer long you don't have stagnate water in the core.

Secondly - Are you sure the water passages on the back of the block are just for the heater? I'd look there. I love your "get 'er done" attitude, but did you not look into that before blocking it off? I assume you must have. What did you find?

To your first argument, I had never heard of that, although it sounds somewhat logical. I put really no thought of that matter into it when I removed the heater core.

Secondly, it's been a while since I took the e28 donor apart, but from memory, it went straight to the heater core. I looked up at Real OEM and it seems to check out in terms of cooling hoses and how they are routed, so I'm fairly certain I'm correct in saying it was straight to the heater core.

Beyond the heater core, it would exit the core and run into a T-shaped hose where one end would come from the heater core, one end would go to the T-stat housing, and the 90 degree end would go to the overflow tank. That, I'm certain of.

Now, I do admit that I never really looked as to WHY the e34 M30s get to block off that passage, and I read some of the influences I used during my swap (like Frank's write up, e30.de, etc) and I could not find who was it that said to use the B35 block off plate in the back of the cylinder head.

And George, I apologize if I come across as "get r done" or if I am sounding like a know it all. I really don't think for a second that I know that much, but I am stumped and have tried a handful of different troubleshooting ideas to try to resolve this, without a slight hint to what the problem might be.... it's a bit frustrating to say the least. I am trying to keep as open a mind as possible to resolve this and carry on with life in an e30 :)

- E

PS: And I knew that about the anti-freeze, although I have yet to see issues (in FL at least) from corrosion of running pure water. I'm sure even in the most tropical of weathers its bound to happen, but if it does, it must be at a much slower pace.

**george graves** · 08-19-2010, 05:17 PM

The "get r done" comment was a compliment. As far as corrosion, yes, it's real. It's simple chemistry - but with that said, it might not matter as I don't see you with the same motor for more than a few years

**Erick** · 08-19-2010, 05:23 PM

Oh, word lol. Nevermind then... long day of troubleshooting. And I'm pretty sure standing in the junkyard hunting for an M30 AFM in 95deg weather fried some critical parts of my brain's comprehension abilities :p

But yeah. I am going to Redline BMW tomorrow. They have a few M30s sitting around to pick up the AFM. With any luck I'll find the coolant piece in the back so we try routing that in.

More thoughts/ideas welcome (and I appreciate the ones thus far!)

- E

**bataangpinoy** · 08-19-2010, 06:33 PM

i dont think its that block off.
i know that spec e30 guys block off a similar hole on the head of the m20's to the heater core and they do not overheat for the most part.
i know that the plate will inhibit flow of coolant, but it should not cause overheating like you describe.

try a different thermostat and go from there.

**Shappa** · 08-19-2010, 06:49 PM

I'm totally against using water for cooling i use evans waterless coolant and love it.
I drift all day no overheating, no boiling and no problems.

Erick i would route coolant port on the back of the head like the m20.

**chadthestampede** · 08-19-2010, 06:57 PM

Originally posted by Coldswede

You may want to keep it connected. They (BMW) removed it in the b35 version of the M30 and there were problems related to it. The hot set-up now for b35 swaps is to install the metal neck from the b34 and re-establish the through flow. Since your racing with straight water you might want to keep the full flow going.

I found this over at mye28.com, I remember reading something about head pipe vs no pipe the other day but I can't remember where. I came accross the thread that contained the above quote in the process. I'll keep searching.

Cooling Line Between Back of the Head and the Thermostat - MyE28.com

http://www.mye28.com/viewtopic.php?t=74626&start=0&postdays=0&postorder=asc&highlight=coolant+back+head

**Erick** · 08-19-2010, 08:01 PM

^ You sir, are the man. I will look into it tomorrow.

**bataangpinoy** · 08-19-2010, 08:21 PM

i stand corrected!

Good info chad!

**chadthestampede** · 08-19-2010, 08:26 PM

Also this

Originally posted by ismellfish2

The coolant flow to the heater core is routed differently on the B35 relative to the B34. The B34 uses a gooseneck from the back of the head, wheras the B35 utilizes a coolant hose that extends from the upper radiator hose back to the heater core on the firewall. If you wish to use the B34 method (the flow of coolant through the head may be superior), it is far easier to remove the cover plate and bolt up the gooseneck with the engine out of the car.

and

Originally posted by Big Bronze Rim

Excellent info, I can't believe I forgot about the water neck and the oil pan. I'm glad that it is all here and well documented with pics. I am one of the believers that the lack water passage on the back of the head on the b35 in the e32 and e34 is what potentially leads to the more frequent HG problems found on those two cars due to the change in the way the coolant flowed through the head.

from this

M30B35 Swap FAQ - MyE28.com

http://www.mye28.com/viewtopic.php?t=60306&start=0&postdays=0&postorder=asc&highlight=coolant+difference+b34+b35

HTH

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