sudden one time smoke and overheat

[pleiadesfella]

hey fellas,

I started my spec b this morning then had to run to the house to grab something and when I came back I noticed the car was spewing some white smoke. normally this doesn't concern me as my car is catless and I live in an extremely humid area so there's always some condensation vapor when I'm warming up the car every morning, but it looked a bit thicker this morning. I needed to get to my workplace to grab a few cables then drive out on a job, so I didn't really have time to think about it. didn't have my accessport plugged in either.

I get to my workplace and right as I'm parking the car, I notice my temp gauge has nearly hit the red. I didn't notice anything while driving and I didn't really get on it (3500rpm at most), and I also started slowly driving it when it wasn't fully up to temp (just under the second thick line but blue light was off). I've actually had this exact situation happen to me before in my gt, but that was due to a burst radiator clamp dumping coolant. today there was no coolant trail and no smoke coming from the rad, so that's not the issue this time. with it being a subaru, I immediately thought it could be a bad ringland but the smoke wasn't bluish. next obvious culprit is the headgaskets and I thought those were toast, but...

I let the car cool down while parked at work then had to drive out on the job. the place I had to drive to is actually right next to my house, so it's the same distance driven. I plugged my AP in and kept an eye on both the AP and temp gauge. DAM was a solid 1.000 the whole time and knock values were also normal (FKL was dead 0 and FBK only went up to -2.80 due to a rough shift into third). I went up to 3500rpm while getting on the throttle and there was nothing abnormal. here's the kicker: the car did NOT overheat by the time I got to my destination. for the whole drive, the temp gauge was sitting where it's supposed to be at the middle. once I was done there, I drove back to work and once again everything was normal. I got out the car and checked to see if it was spewing any smoke and there was nothing. I did have some odd cylinder 1 roughness readings while parked at work, but that wasn't present while driving.

it's not the warmest day today (especially not in the mornings here) so I'm really lost as to why the car would have overheated like that only once but not again after another identical drive. bad hg would be the easy answer but then it should have kept overheating. the thicker white smoke on first start up was strange too, though I can just chalk that up to higher than usual condensation as we've had very warm and very rainy days recently. I want to say its either a rad fan engagement failure (the fans have been clicky recently) or blown turbo seal or at least something related, but what I'm reading on other forums doesn't line up to what just happened to me. I'll definitely check my oil later today when the engine is cold.

I'm just hoping someone here has a better idea of what might have happened lol. thanks.

Edited July 20, 2023 by pleiadesfella

[m sprank]

Not enough info.  Could have been a stuck t-stat, could be a rad cap going bad, could be too many things still.

[KZJonny]

I'd be inclined to pick up a radiator/coolant system pressure testing kit and have a look at what those results get you perhaps?

The $80 it's going to cost to pick one up off Amazon is a lot less than removing and machining warped heads...

I know how much Mike hates throwing parts at problems but.... How recently was the cooling system flush and filled with new coolant? Again, a system flush and a new (OE) thermostat are not a lot of money. If done recently, the coolant can be recovered, filtered and re-used. Thermostat can be easily checking in a pot of water with a thermometer in it for proper opening temp and spring force, to a degree.... Rad caps are cheap, if age is unknown and you have any doubts. This is all just maintenance stuff anyway, so it's not as tho you end up being behind if you do it all.

[m sprank]

Not against maint items.  Cars are not getting any younger.  It might "fix" whatever the ailment was, I just hate not knowing. 

[pleiadesfella]

38 minutes ago, KZJonny said:

I'd be inclined to pick up a radiator/coolant system pressure testing kit and have a look at what those results get you perhaps?

The $80 it's going to cost to pick one up off Amazon is a lot less than removing and machining warped heads...

I know how much Mike hates throwing parts at problems but.... How recently was the cooling system flush and filled with new coolant? Again, a system flush and a new (OE) thermostat are not a lot of money. If done recently, the coolant can be recovered, filtered and re-used. Thermostat can be easily checking in a pot of water with a thermometer in it for proper opening temp and spring force, to a degree.... Rad caps are cheap, if age is unknown and you have any doubts. This is all just maintenance stuff anyway, so it's not as tho you end up being behind if you do it all.

you make a good point on the coolant. I'd need to check receipts to see when it was last changed, because it was not done under my ownership. though I never had any doubts about the coolant until now because I found the cooling in my spec b to be better than in my gt. I'm probably going to get a flush, a new rad cap and new thermostat like you said. not going to invest $80 in the testing kit - not that I don't want to, rather I can't justify the cost currently since we're in the middle of a move and I'm probably not going to see my spec b for a while as it's going to storage in september. would rather just throw the money at the car to get it fixed outright for now.

as for the issue itself, I'd love to give more details but it was just very strange. I just drove the car home and back again (and pushed it on both trips) and it was fine once again. AP tells me the turbo is still healthy and boosting to 20psi consistently. I don't see any smoke or leaks coming from anywhere on the car either. didn't have the chance to check the oil yet, but something tells me it's probably going to be fine too.

so from what I gather it could be the thermostat and/or rad cap going bad possibly coupled with old coolant since the car seems mechanically healthy.

thanks guys, I'll get these done soon. I was just really worried that my spec b was going to be completely out of commission since my gt also developed a bad misfire last weekend and left me stranded, so if my spec b also went I'd be carless in the middle of moving out of here. can't afford to have a catastrophic failure now of all times, so I'm glad the problem and solution both seem simple now  

[SoobyDoobyDoo]

Check your rad cap. Wife’s Tribeca was running a little hot here and there but not all the way in the red…rad cap o-ring was torn. Replaced with an oem and it seemed to do the trick. Also had the cross over pipe recently replaced so it got new coolant. I’d start there…

[pleiadesfella]

just checked my coolant level, rad cap and dipstick the other day. oil wasn't milky on the dipstick, so I don't think any coolant mixed with oil. but my coolant level was dangerously low and I hadn't realized this before, I'm pretty sure it was fine months ago so there must have been a slow leak. rad cap looks fine to me, but I think y'all would be more knowledgeable about it. pics below

 

[NORULZleggy]

Fill it up, and just get a new oem rad cap. I would buy two lol. Just to ease your mind.

[m sprank]

IIrc cap at turbo res and cap at radiator are different pressures.  Make sure to use the correct ones and replace both.

[pleiadesfella]

yeah I noticed the different pressure ratings between both the caps, I'll be sure to get the round OEM cap rated for 137kpa. I did some more searching and found a thread on the outback forums where someone had a sloshing sound coming from their dash, and their car ended up overheating in a very similar way to mine one day. my spec b also sloshed like crazy on some cold startups, but I always assumed this was the ac system being weird in some way since that's what a local mechanic told me when I brought the car in for it. a bad rad cap causing sloshing and issues with the coolant overflow tank and subsequently overheating makes so much sense now though.

I'm about to put an order in for a new oem cap, and will get an appointment for a full coolant flush asap. thanks guys  

[pleiadesfella]

update on this: the car actually kept overheating later on. every time I'd drive to work the temp gauge would keep rising past regular operating range, though my workplace is close so it never hit the red. I took it to one shop in town and they said it was likely the thermostat sticking, but they also said they didn't work on subarus due to them being boxers, so they referred me to another shop in town which gave me an appointment for today.

after all the wait, the new thermostat was installed today alongside a fill of fresh coolant and now it's back to working like a charm. hopefully it stays that way lol.

I still do plan to get a new rad cap, but for some reason they're impossible to get at a good price in canada? they're usually listed for $30 which is great, but then the shipping is $40 for such a small part and I can't justify it. will probably get it ordered in from the dealer at some point, I imagine they would have at least a few on hand.

[KZJonny]

I just got both of mine from Subaru this morning.

45137FE002 - $39.49

45137AE00B - $21.96

Both prices are tax in. The parts department at my local Subaru dealer is giving me, and presumably others like me with ‘heritage’ cars a 15% discount on parts to help keep them going, ostensibly.

Probably not a bad idea, if they want to keep bragging about what % of 10 year old Subarus are still on the road.

[Max Capacity]

Most auto part stores will carry radiator caps. I got one from NAPA a few years back. Seems there are only a few types of caps, so you really don't need to have a Subaru one.