E36 Thermostat

December 3rd, 2008 Leave a comment Go to comments

The thermostat and radiator hoses are integral parts of the cooling system, so you’re going to have to drain all of the antifreeze first, and then remove the fan to get to the thermostat housing.

Now I don’ think there’s a specified interval for a thermostat and radiator hose change, but I’ve got 50k miles and I just changed out the water pump so I figured what the hell, all of the crap was off so I might as well. The hoses were kinda thin at the ends, and the water temperature DID go up quicker (i.e. the thermostat opened sooner) after I put in the new thermostat. But change ‘em when you feel like you need ‘em.

By the way, the stock thermostat opens at 88 degrees C, or at least that’s what’s printed on it. You could get one that opens quicker at 55 degrees C (BMW P/N 11-53-1-417-215) off of one of the group N race cars, but I’m not sure if it’d fit or how you’d find it, and I’ve seen aftermarket ones that open at 70 degrees C for about the same price as the stock one. So, here we go….

Cost: This cost me about $80 cuz I bought it from the stealer w/ my 20% BMWCCA discount; if you get it mail order, it’ll definitely be cheaper.

Time: I estimate this should take the competent do-it-yourselfer about 2-3 hours, the newbie about 3-4.

Skill level: If you can bore out your engine cylinders with hand tools, then you can do this and pretty much anything else you want to do.

radiator hose (upper?) (BMW P/N 11-53-1-708-499) list $31.73
radiator hose (lower?) (BMW P/N 11-53-1-726-344) list $42.84
thermostat (BMW P/N 11-53-1-721-002) list $34.97
O-ring, thermostat (BMW P/N 11-53-1-265-084) list $3.03
gasket, thermostat housing (BMW P/N 11-53-1-740-437) list $3.25
4 expensive hose clamps (BMW P/N 07-12-9-952-119) list $3.14
radiator drain plug (BMW P/N 17-11-1-468-467) (list $4.26)<–optional
1 gal. BMW antifreeze (BMW P/N 82-14-1-467-704) (list $20.93)
crush washer for the engine drain plug (BMW P/N 07-11-9-963-200) (list $0.88)
1 gallon of distilled water–more or less, depending on the ratio–go to your supermarket

First you need to drain the coolant. Then you take the fan off.

This is what you see when you take the fan off. The black thing in the middle is the thermostat housing, and the two arrows point to the lower (left side) and upper (right side) hose clamps. Unscrew these until the clamps can slide freely. Then pull the hoses off. I found that if you take a small, flat bladed screwdriver and kinda lift around the end of the hose you can peel them off easier.

Here is the upper radiator hose, the clamp the blue arrow is pointing at should’ve been removed in the last step, but I drew that in and was too lazy to take it out. Anyway, the red arrow with the cool looking’ international symbol for ‘DOH!’ is pointing to the hose clamp that attaches the hose to the upper radiator neck. THIS NECK IS PRONE TO SNAPPING OFF so watch out! You break this and it pretty much means YOU HAVE TO BUY A NEW RADIATOR or get all MacGyver on that thing to make a new neck. Just be careful. To get this off, I would take a small, flat bladed screwdriver and kind of lift the edges of the hose up off of the circumference of the neck.

Here’s the clamp holding the lower hose to the radiator. Same thing, unscrew, be careful, get the hose off.

To get the thermostat housing off, use a 10mm and 13mm socket in the areas in the picture. There are four bolts, you kinda hafta feel for ‘em.

After you remove the housing, you should see the thermostat where the arrow is pointing. Pull it out (note: mine took a little effort to get out. Just pull)..

Put the funky looking’ gasket in the thermostat housing, and remember to lubricate it with antifreeze so it doesn’t dry out. Put the O-ring on the thermostat and do the same thing with the antifreeze–lube it up like you waxin’ yo’ jimmy. WTF? Anyway, note the small arrow imprinted on the thermostat–this should point up when you reinstall it in the block since it’s the orientation of the vent hole. Put the thermostat back in the block and then put the cover back on. Torque the bolts to the specs at the beginning of this procedure. Slide the hoses back on, remembering to put the hose clamps on the hoses first before putting the hoses on and also being VERY CAREFUL WHEN PUTTING THE HOSES BACK ON TO THE RADIATOR. Tighten the hose clamps, but don’t go too tight ‘cuz you can break the necks.

Replace all of the coolant and then put the fan back on. Ta da! That’s it. Look for any coolant leaking from the hoses or thermostat housing in the next couple of hours/days. Take note of when the water temp reaches the mid-point–it should be sooner.

If you have any questions, comments or corrections on this procedure or just have some amusing anecdote then email me!

version 7/20/99

Copyright © 1999 by uberjeph. All rights reserved. Blah blah blah blah. Thanks to posts by Martin Miller and countless others who didn’t even know that they helped me…

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