I have a 2005 R53 with about 150k miles on it. Bought it used, it included Dinan badges, exhaust, and intake. It probably came with a Dinan bored out throttle body originally, but that was replaced as bad by the Subaru dealer we bought the car used from before we got it. It also has full suspension upgrades (Koni coil overs that lower it and spring it stupidly hard, stuff that I want to remove and move it back to stock, because I am not doing SCCA racing with the thing, just have fun driving it around town). Very likely to just have been a commuter car it's whole life... it was origonally registered to a woman at University of Pittsburgh (still had the parking pass sticker when we got it), and after it came to Cincinnati, I don't think it hit any of the SCCA stuff. We have always used it as a commuter, and I am the only one that drove it hard, but just for cloverleafs and back roads, and nothing very crazy. The motor has had an easy life.

It has been passed around the family. I've done lots to the car, including replacing the clutch, all without a lot of drama. Once you just suck it up and take the time to put it in service mode, it is a surprisingly easy car to work on.

While the car was "away at college" where I couldn't keep a good eye on it, it had an overheating issue. I rescued it the first time with the exploded T valve, replaced it in a parking lot, and chalked it up to 20 year old plastic. It started fine and idled a little rough but not bad, so I thought it was sorted, and gave it back to the kid and came home.

They made it about 10 miles when the T blew again, and they coasted into a used car lot in a cloud of antifreeze smoke. I made rescue trip #2, and tried limp it to a local shop after a quick patch. Made it there by driving short distances watching the temp gauge, then stopping until it cooled again. Nothing blew that time. They waited two weeks, just to tell me "yeah, the last time we worked on a Mini cooling system, everything went sideways, so we aren't touching them anymore, and the local mini shop we know has a months long waiting list". So I got the Uhaul dolly, trailered it home, and it sat parked for about a year until I could get to it (had an extra car kicking around the family, so no rush).

So, last weekend, I finally got around to working on it. New water pump, new hoses, new thermostat, new belt, new tensioner, supercharger oil change, etc. I found the alternator seized and replaced that (rebuilt Denso from Rock Auto for $169). The car sat for a year, so no idea if that was happening when the overheating was happening or not. The belt tensioner was not tensioning very well at all, and the belt was badly stretched and cracked. I tested the old thermostat in a jug of boiling water, and it never opened.

Lots of little fussy work, but it went fine, and I put it all back together.

(You know where this is going, and I knew there was a pretty good chance it was going here even before I started the job : ) ).

So I buttoned it all back up, put in $50 with of BMW coolant, and started it back up. It was missing badly on at least one cylinder, and blowing low to moderate amounts of white smoke. I idled it for a while, revved it more, and it stared blowing prodigious amounts of white smoke. In hindsight, I should have pressure tested it, but I don't have anything rigged for that, so I took the chance that the work I did was all that was needed, and if it wasn't, I would deal with it then. Which, here we are. Looking back, still probably not a bad decision, replacing the head looks like it can all be done from "the top".

This car was overheated HARD at least twice. Once that T blew, the car was pulled over, but it blew twice. And it was "hot" but not "blow up hot" for another drive.

No chocolate milk in the oil or oil fill cap. Looks clean and new. But it hasn't been driven far with the problem, it blew up first. ; )

And, I have some karmic guilt I need to repay. I had a 2001 Saab 9-3 that I ***loved*** that came up with no pressure in two cylinders (@160k miles and starting to rust). I was going to fix it, but found a 2006 Saab 9-3 Aero for a stupid low price, and just bought that instead. So I let it go to a scrapyard, even though it was probably just a head gasket. That 2001 was a much more special car than the 2006, which was great in every way, but not "special" like the 9-3 hatches were. So, I owe the universe for letting that 2001 go when it could have been fixed. This feels like a chance to make that up, because the R53 is another genuinely special car. Maybe even more special if I am honest, but I am a pretty devoted Saab guy. : )

So, a few questions for the collective.

Researching, it appears that the oil cooler can have similar symptoms. But I have a bad misfire, which suggests to me it is a head gasket, and not an oil cooler. Any second opinions on that reasoning that would convince me to check that before pulling the head?

Best case, the head gasket is gone. Medium bad case, the head is cracked. Worst case, the engine has some deeper damage. I am hoping for a bad head gasket, kind of expecting a cracked head, and because beside the smoke everything sounds absolutely perfect I don't think there is deeper engine damage.

I see a few heads out there for sale on eBay, $500 ones looking uber sketchy, and some $1000 ones that look pretty legit. If the head is cracked, or even if it isn't, is there a reputable source for fairly priced stock heads? For my Buell, I would have just pulled the head, put it in bubble wrap and send it to a guru like Pammy from CyleRama, and they would sent it back perfect and bill me. Is there somebody like that for R53 heads? Somebody who cares? This is a "spare" car, so time isn't an issue. Or, even a Cincinnati area shop that does good work (not necessarily quickly). I do a lot of my own work, but given the head probably needs an expert looking it over, I wouldn't be opposed to paying a fair wage to have it sorted.

What are peoples thoughts on the likely hood of blow gasket vs cracked head? I am kind of inclined to rebuild the head either way once it is off.

I will replace the timing chain tensioner and guides in there while I am in there, and replace all the gaskets and seals I touch.

And finally, we are moving in a couple of weeks. The new house is .8 miles from my current house, and all back roads. I am inclined to fire the car up, drive it over there watching the temp gauge closely and coasting a lot, and coast it into the new place. Is this staggeringly stupid? Or more in the "not entirely safe, but you would probably do it too" stupid?

Thanks for any advice and experience all!

 

The miss is related to the firing system not the cooling system. Doesn't sound as though you've replaced many of those parts -- coil, plugs, wires, etc. It could also be a valve issue. You can grab an endoscope cable for cheap on eBay or Amazon that works with your phone and an app to check out each cylinder for valve damage. Unfortunately, the only way to determine if the head is bad (in the absence of coolant in the oil) is to remove it, have it examined by a competent shop and possibly resurface it. Worst case it's unusable and you're out a grand.

 

At low RPM, it is a bad miss. At higher RPM, it smooths out, so I was thinking it was a miss due either to lack of compression or just too much coolant leaked in to fire. But now you have me thinking, that can't be the case, or I would have been over pressuring the cooling system. I guess if the cooling system is pumping too much coolant into the combustion chamber where the head gasket had failed, or where the head is cracked, that could cause the low RPM misfire. The engine sings beautifully at high RPM... while ejecting a MASSIVE mushroom cloud out the exhaust. : )

It is blowing a TON of white smoke out the back, and it has that sickly sweet coolant smell, so coolant is getting into the combustion chamber somewhere.

Good advice about the scope and checking the ignition parts, thank you. I already have a scope (but I think it is packed up for the move, so inaccessible for a few weeks), that is worth doing. And the coil was replaced about 30k miles ago, but could have been scalded by one of the exploding T fitting events. And I should look for fouled plugs as well, that could be a hint at which cylinder(s) have the issue.

Thank you for the suggestions!

 

Finally got the chance to pull it all apart. The head gasket had for sure failed, you can see the clean cylinder that was getting the coolant, and witness marks on the head and head gasket. It does not look like the head is cracked, but unfortunately, the camshaft is pitted in several places. Oh well, at this milage, I should really be putting in a completely rebuilt head regardless.

Now off to go headhunting.

 

Good excuse to put a ported head and performance camshaft in!

Those dang coolant tees. One got me a couple of years ago at similar mileage so I put a used, much lower mileage engine in my car, replaced the entire cooling system and it's been fine since. Well, the engine and cooling system anyway. I have begun to collect metal cooling system parts to replace the plastic parts and at my convenience, I put them in the car. So far on my car I have the metal bleeder pipe on the upper radiator hose and metal thermostat housing. Yet to install are 2 of the 3 tees. I think I'll wait until I have the third tee because those will not be fun to mess with and I only want to go in there once.

The camshaft in my original engine had the same wear. It seemed to be contained to the exhaust lobe on cylinder 1 so I don't think it's a lubrication issue but a material defect because several other R53 owners have reported the same wear.

 

Thanks for the info ghostwrench. In my case I thought the T was the culprit, but it was the symptom. The thermostat was stuck shut. :(

Oh well, good to catch the cam before worse things happened anyway. This is a spare/hobby car, so the downtime isn't a big deal. And remanufactured heads look pretty affordable on ebay.

 

It's amazing how your experience mirrors mine!

Once I got the engine installed and running, I was overheating very quickly. Since I knew my cooling system was holding pressure, I pressure tested the expansion tank cap. It did not hold pressure and so I replaced it. Still overheated. Then I replaced the thermostat - which was only about 1.5 years old and that solved my overheating. But I don't know what happened first - the tee breaking or the thermostat stuck closed. I had never had a high coolant temperature until the actual failure.