deedub 88 Report post Posted 5 hours ago 21 minutes ago, Vass said: Some see it as an "upgrade", the logic being lower pressure = less strain on the plastic & rubber components in the cooling system = longer life for the cooling system components. The counter argument is that lower pressure = lower boiling point = higher chance of vapours in the system. Gases don't transfer heat nearly as efficiently as fluids, leading to localised hot spots or hot pockets in the engine, which obviously isn't good. This is interesting. Thanks for the explanation. 3 minutes ago, gjm said: As suggested, stick with original spec if possible. Yea I'm probably going to do some preventative maintenance on the cooling system while giving it a flush. I'll be ordering the OE cap. Quote Share this post Link to post Share on other sites
Neal 565 Report post Posted 5 hours ago (edited) 1 hour ago, deedub said: Just noticed that my coolant reservoir cap on my 98 E36 318is has a 1.4 bar cap. Checked real oem and it should be 2.0 bar. Trying to understand if there's a reason PO would intentionally replace with lower pressure cap. May have just been the best option available. Lower pressure could also be a result of the 90s e30 cap recall. There was concerns around pressure build up and scolding an unsuspecting owner.This one was for m20s and I remember being sent a new cap for my 84 323i https://bmwtechinfo.bmwgroup.com/sib_attachments/B170293.pdf and https://charm.li/BMW/1984/318i (E30) L4-1766cc 1.8L SOHC (M10)/Repair and Diagnosis/Technical Service Bulletins/All Technical Service Bulletins/Recall - Coolant System Overheating/ Edited 4 hours ago by Neal 1 Quote Share this post Link to post Share on other sites
