Triangle42 Posted July 27, 2021 Report Share Posted July 27, 2021 When removing the heater core from an e30 with an m20 do you just block off the water port on the back of the head? Or do you reroute the water back to the front to keep from creating a hot spot in the head? Quote Link to comment Share on other sites More sharing options...
Black Magic Posted July 27, 2021 Report Share Posted July 27, 2021 Not a BMW expert, but in all of the other cars I have prepared I bypass the heater core by using a loop of hose with a metal restrictor in it. This allows some coolant to flow through the oem path (was the heater) but prevents excessive flow through the circuit. Cars I have helped work on that have the heat\block ports blocked are harder to bleed all of the air out of. Also I have seen several rubber caps fail when used as blockoffs. I think it is actually hard to find caps built to the same quality as proper cooling system hose (that has been looped). I think in the end if you are willing to "do it right" blockoffs can be done, just most of the ones I have seen either are clearly air traps and or future leak paths. 2 Quote Link to comment Share on other sites More sharing options...
MichaelPal Posted July 27, 2021 Report Share Posted July 27, 2021 (edited) 2 hours ago, Triangle42 said: When removing the heater core from an e30 with an m20 do you just block off the water port on the back of the head? Or do you reroute the water back to the front to keep from creating a hot spot in the head? block it off. I just cut the extra material off the tube and JB weld the rest of it shut. Bolt it back in place with a stock gasket + fasteners. I’ve run it like this for 4 years. the head gasket helps route the coolant in the correct manner between block + head. Edited July 27, 2021 by MichaelPal Quote Link to comment Share on other sites More sharing options...
enginerd Posted July 27, 2021 Report Share Posted July 27, 2021 (edited) Most people block it off, I routed mine back to somewhere on the thermostat body. Edited July 27, 2021 by enginerd Quote Link to comment Share on other sites More sharing options...
TimS Posted July 27, 2021 Report Share Posted July 27, 2021 I made a block off plate out of 1/4” aluminum. People do make block off plates pre made. Quote Link to comment Share on other sites More sharing options...
Rodger Coan-Burningham Posted July 28, 2021 Report Share Posted July 28, 2021 In general, the headgaskets have orifices of different size that the pressure from the pump create the proper flow through the head along the way to the back of the engine. Depending on where the flow comes off on the heater hose and where you return it to, you can help or hurt by looping it. Not sure on the M20 where this is, but the general consensus on most engines is you can block it off with no issue. If you loop it back to the water pump, you are bringing coolant that has made a trip through the head and picked up heat back into the flow that will tend to go back to the engine. Granted, some of that will be directed to the radiator by mixing and then through the thermostat to the radiator. As mentioned, some times blocking off makes getting air out a bit more difficult. A whole bunch of words and no answer to your question. I should be in Washington DC. 2 Quote Link to comment Share on other sites More sharing options...
TimS Posted July 28, 2021 Report Share Posted July 28, 2021 Connection is on back of the head up against the firewall. I believe that the heater core has a control valve that when heat is not required it shuts off water flow, so blocking the port on the head is the same as never using the heat. I have run it both ways on my car. Previous owner had it looped back using the hose that looks like a giant tee that connects to the expansion tank and the tstat housing. I removed the whole thing last time I had engine out just to simplify things. Quote Link to comment Share on other sites More sharing options...
Triangle42 Posted July 29, 2021 Author Report Share Posted July 29, 2021 Thanks for the help 1 Quote Link to comment Share on other sites More sharing options...
Indysupra Posted July 31, 2021 Report Share Posted July 31, 2021 I welded both of ours up. Quote Link to comment Share on other sites More sharing options...
atxe30 Posted August 1, 2021 Report Share Posted August 1, 2021 i did this deal. had too many other things to do to work on a solved problem: https://www.condorspeedshop.com/collections/e30-parts/products/m20-coolant-block-off-plate-e30 Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.