Cooling system conversion to late model

#1

Two laps into the first of two races on Sunday and my radiator sprung a leak. Unfortunately, since I have the old style cooling system, the only spares I could find in the paddock were new style radiators. The local auto parts stores didn’t stock this radiator, either. So my weekend was effectively done.

I almost had the same problem last race weekend when I shredded my lower hose on the alternator fan (not motor mount related). Took some creative splicing and a liberal application of rescue tape to get me back on track for that one because, again, no one had spares for old cooling systems.

Which brings me to my decision to upgrade the cooling system to the new style.

So I have a few questions:

  1. Does anyone have a spare expansion tank they’d be willing to part with on the cheap?

  2. Can someone confirm my understanding on parts I need to switch / add?

  • Expansion tank
  • Water pump
  • Radiator
  • Metal pipe (#8 in the image below)
  • New model timing cover (for the metal pipe to bolt into)
  • New hoses (see next question)
  1. In my current setup, I’ve eliminated the hoses from tstat-to-TB, tstat-to-heater core, TB-to-block, and head-to-heater core. As such, I’m not 100% clear on which hoses I still need converting to the late version. Based on the image below, I think I need:
  • #7 – lower radiator hose -to- metal pipe
  • #11 – metal pipe -to- tstat
  • #4 – upper radiator hose -to- tstat
  • #1 – water pump -to- tstat (which is the same hose as on the old style)

What I’m not clear on is what to do about #13, which appears to be a 3-way hose that connects the tstat to the expansion tank and, I’m guessing, out to the heater core. Can I just replace this with a generic hose from the tstat? If the normal hose location on the tstat is the large diameter port, while the expansion tank might be a small diameter port, I’m thinking I can just buy the smaller diameter hose and plug it into the port on the tstat that normally goes to the throttle body, since I’m not using that anyway.

Confirmation/suggestions would be appreciated, thanks! :slight_smile:

Som

#2

If you are determined to install a late model radiator, all you need is the steel tube. Just use a little imagination to fasten it to the front of the engine.

The early model cooling system isn’t inferior. You just have to do something to ensure the lower hose doesn’t hit the radiator. Maybe you are missing the steel hook that is inside of the left framerail. That hook helps a lot to hold the hose away from the alternator.

The early pump has a T that goes to the reservoir. The late pump doesn’t have the T, but does have a fastening point for the steel tube. It’s entirely do-able to use a late pump and then fab a T for the reservoir. There’s lots of ways to skin this cat. For about a year I didn’t use a reservoir at all. It was there in order to be legal, but no hoses went to it.

#3

Makes sense, thanks! I agree, I don’t think the early model system is particularly inferior. I’ve got a zip tie on the lower hose and it works just fine. Plus it sounds like some people like the early systems having something to do with being easier to do certain repairs (distributor removal or something?).

I think my determination comes more from the potential availability of spares than anything else. Everyone running the old model cars that I asked seemed to have converted to the new cooling system. If something stupid happens and I forget to put the zip tie on or whatever. Or say my water pump goes. Or a hose starts leaking. Or I take a rock through my radiator. Individually very unlikely scenarios, I know. But since I’ve had back-to-back weekends with these problems, and have had back-to-back weekends of finding helpful people that had spares – but for late model systems, it feels only natural to convert just to make myself more resilient to these kinds of issues in the future.

The other option is I keep spares for every old system part, which, besides the cost, also adds to the bucket of spares I lug to the track every race weekend. Then again, saves me from having to touch anything on the car other than the radiator.

Decisions, decisions. :slight_smile:

Som

#4

I take a spare old and new water pump, old reservoir, old and new caps, and most hoses to every event. Sometimes I take an extra radiator. Even if you don’t need those parts this year, someone else will. It’s not a matter of just bringing parts for yourself.

We’re SpecE30. We look out for each other.

#5

I agree with that – so if I’m really the only one running the old system and EVERYone else seems to be running the new system (even the old model cars seem to have been converted), then me bringing spares is really only helping myself and not really contributing to the group anyway.

So I can be the lone wolf running an old system with spares for myself and the occasional old system car, or I can convert to a new system and build up (over time) a set of spares to help contribute to others should they face cooling issues.

Som

#6

There’s no strong arguments for or against either system. It’s going to come down to personal preference. More important is simply to delete every hose that isn’t absolutely necessary. Every hose is a failure point.

One hose to delete is the one that goes to the back of the head. The new reservoir will complicate that a little bit, but any hose you can delete is worth doing. Deleting that hose also gives you a bit more clearance behind the head and there’s a couple tasks where that’s handy.

#7

Agree again. :slight_smile: While replacing the head, I capped off the coolant passage at the back. All my heater hoses are gone, as are the hose lines to the throttle body. Also moved the OP switch to the coolant barb spot in the block. Side note… kinda wonder if 7psi is slightly too high for a coolant pressure switch. My light didn’t seem to go off until a few laps into each session.

Sounds like I can just run a generic hose from the thermostat housing’s throttle body barb to the expansion tank and call it a day – no need for the 3-way hose.

Som

#8

Re. coolant pressure switch. The pressure from the pump alone isn’t enough to turn the 7psi switch off. To hit 7psi requires the combo of pump and heat, so the pressure switch won’t go off until the engine gets hot.

Certainly possible tho that your pressure switch is wanting a little more pressure than usual to trip. My coolant pressure light goes off before the thermostat opens, certainly before I get on the track.

If you are curious as to what is going on with the pressure in your cooling system under different conditions, you can put a coolant pressure system tester gauge on your reservoir. Then watch what the gauge does at different engine temps and rpms. A coolant pressure system test kit can be had at Harbor Freight for not much. Comes with lots of adapters for different cooling systems.

#9

Good idea… I’ve got a pressure tester… I’ll hook it up and see what’s going on. The sensor is actually pretty new, as the one on the car was leaking when I bought it beginning of last year. I’m running a 71 degree thermostat… maybe that has something to do with it?

Side question – the Mishimoto aluminum radiator (MMRAD-E36-92) – can this be made to fit the '87 cars using any spec-legal changes? My trigger finger bought this off Amazon and realized 5-minutes later that it apparently only works for 88+ e30s through 99 e36s. Fortunately I was able to cancel the order.

(Edit: Now I’m wondering if the reason it’s marked as '88 is simply because of the outlet configuration, rather than a pure fitment issue. Can someone confirm this? If I’m swapping to the late model system, this radiator should work fine, right?)

Som

#10

Anything can be made to work. I’ve been using a variety of aftermarket radiators for a while now.

Colder tstat just impacts the temp that water starts flowing. It doesn’t impact steady state pressure or temp.

I did a little test as I was putting the car in the trailer this afternoon. 140deg and idle and my 7psi pressure switch in the block was closed. At 3k rpm the pressure apparently went >7psi because the switch opened and the light went off.

#11

You keep mentioning that you’re the only one running an early style cooling system! Not true. Are you forgetting the guy that parks next you every single race? Looks like now I’ll be the only one running an early style cooling system :frowning:

#12

Oh! Shit, I forgot. So you’ll be at the September Sonoma event with me??

#13

touche

#14

Couple more questions cropping up for me on this as I finally have time to wrap this up for the September event.

  1. To get the Mishimoto radiator in, I removed a loose fitting bracket that was sitting (unbolted) below the early-model radiator. That allowed the radiator to sit low enough to align the upper radiator mount perfectly. That said, in this diagram there’s a couple mounts that I hadn’t noticed/purchased (#6 and #7):

The radiator appears to fit fine and snug, though I haven’t exactly yanked it in all sorts of different directions. I’m not even sure the Mishimoto would fit in those plastic mounts. In its place, though, is there additional lower mount work I should be doing to secure the radiator? There was a r3v thread that suggested welding additional mounts, and this thread suggests adding rubber plugs – http://www.r3vlimited.com/board/showthread.php?t=89055. I believe his car was an '86, though. Would my '87 be different – maybe it already had the rubber plugs? Any chance I’m good without the mounts?

  1. Realized that I never looked into how to mount the late model expansion tank. It appears I need at least this part #10 in this diagram:

But there’s nowhere on my wheel well to mount it. Plus, when I position the tank on the wheel well, it looks like the bottom hose goes straight into the airbox mount or the ABS hard lines – depending on how high/low I go over the wheel. Lastly, there appears to be a hinge on the opposite side of the mount that I’m guessing wedges into a body part that’s not on my car (not sure how I go about finding a part number for that).

… am I missing something here or is this where I “get creative” and weld my own brackets up?

Thanks for the help!

Som

#15

Feel free to do some imagineering in order to fasten your coolant system bits down. No one’s going to care.

Radiator. I have a big aftermarket triple pass radiator. The bottom sits on the same rubber buttons on the lower radiator support as the OEM rad, but I have some flex ties that help hold the bottom end in place. Then I fabbed a bracket that goes on top that firmly holds the radiator in place. My point is that you shouldn’t feel constrained into making the OEM rad fastener bits work.

Coolant reservoir. For a while I didn’t even have one. A bit later, in order to be legal, I put one in, but didn’t connect hoses to it. My radiator has a cap so I can use that to pour in water. I’ve read that you do want a “still volume” of water tho, and this is what the reservoir provides. The still volume allows air to come out of solution. But some rads have this integrated into the rad design. I do not know how significant the “still volume” issue is tho, maybe it’s not a big deal.

I’ve never installed a late model reservoir so I can’t help with details re. how it’s mounted.

#16

Thanks, Scott.

I think I just have the radiator sitting on the “rubber buttons”, as you called them. Am I taking a big risk running it like this? It seems firm, but over the course of a race I’m sure it’ll see more sudden forces and vibrations. I’m sure I’ll at least try zip tying as best as I can.

Interesting about the still water – never thought about allowing the fluid to “exhale”, so to speak.

Does anyone, by chance, have a photo of their driver’s side fender without the coolant tank in place? It looks like there might be some brackets I might need (maybe something on this page http://www.realoem.com/bmw/enUS/showparts?id=1413-USA-05-1990-E30-BMW-325i&diagId=41_0150 or this page http://www.realoem.com/bmw/enUS/showparts?id=1413-USA-05-1990-E30-BMW-325i&diagId=41_0167).

Otherwise I’m just going to just ziptie the hell out of it, I guess. :slight_smile:

Som