Exhaust smoke/Running hot on startup after A/C being on

[98_Q45]

This has been an issue since I’ve owned the Q, but it still kinda bugs me that I’ve not been able to resolve it.
Coolant full, fans working, oil can be fresh and new, I do stop leak/seafoam but: I still get some bluish/grey smoke on acceleration especially after idling at lights or drive thru (which I try to limit). The longer I idle, the more seems to build up and takes longer to clear out.


Also whenever temperatures start getting in the mid 90s-100+ range during the day, I’m not running hot while driving but after being on the highway and then turning off to get gas or run to store, I’ll start back up and next thing I know the temp gauge will creep up to near the 2nd coolant line.

The issue was worse when my timing sensor was off center, and has since improved. However there was a ride last year where the temperature was 105 degrees, with 110 coming off the pavement. On 2-3 occasions I started to run hot, at one point even the needle was moving away from half point while on the highway. I had to cut the a/c for awhile.

No A/C running I don’t have the issue. Idk if it’s head gasket or converter. I lose a minimal amount of oil and coolant. Mostly oil versus coolant though.

Considering it seems a bit too in depth to chase, I’ve thought about tail pipe filters or replacing both sides exhaust line. But I only imagine the cost versus some of the ones I’ve seen online. Ideas?

[VStar650CL]

Your little puffs of blue under load are probably from worn valve seals. Not a big worry as long as you're not losing a lot of oil or fouling plugs.

The temperature issue sounds like you have a slight flow problem, either air or coolant. Something is marginal, either a weak fan clutch or a restriction in coolant flow (often some plugged radiator tubes or a partially-collapsed hose). It's creating a situation where the temperature is fine under normal conditions but the system can't handle the combined extra load from the A/C condenser and a very hot day.

[fontana dan]

Your little puffs of blue under load are probably from worn valve seals. Not a big worry as long as you're not losing a lot of oil or fouling plugs.

The temperature issue sounds like you have a slight flow problem, either air or coolant. Something is marginal, either a weak fan clutch or a restriction in coolant flow (often some plugged radiator tubes or a partially-collapsed hose). It's creating a situation where the temperature is fine under normal conditions but the system can't handle the combined extra load from the A/C condenser and a very hot day.

Would a weak fan clutch cause increased coolant temps at highway speed? What would be the best way to diagnose a weak fan clutch? I recall a method of letting the car idle and heat soak and then try to stop the cooling fan with a rolled up newspaper.
The fan on my Q45 is virtually silent in all situations. I never hear it. I've also never seen the temp gauge budge since I replaced the radiator with a high-quality Denso unit. Original fan clutch. I replaced the clutch when i replaced the cooling fan (cracked, something else to look at regarding high temps), and the aftermarket unit was junk. straight in the trash can. damned aftermarket parts.
In my head I would imagine that high temps on the highway would indicate a coolant flow problem, or perhaps a restriction of airflow through the radiator itself, possibly debris clogging the fins.

[VStar650CL]

There will be a bimetal coil on the front of the clutch, just spin the fan with it cold and then hit the coil with a torch or barbecue lighter for a few seconds. Spin it again and you should feel a major increase in resistance. If you don't, the clutch is shot. It seems from your description like you're getting a mix of conditions where it heats up, so I wouldn't rule the clutch out. It still needs to work when you drop throttle on the highway. But I do agree that air restriction or coolant restriction of some sort seems more likely.

[AZhitman]

All of the above, and I'd add that the condenser is in front of the rad, so flushing it from the back can help. Also, and you probably remember this from way back, people typically run WAY to much coolant vs water ratio. In a hot climate, the coolant is just to lubricate the water pump and prevent corrosion. I've always had great results with 1 qt of coolant, 2 bottles of WaterWetter, and the rest is distilled water.

[fontana dan]

I thought about this thread today while driving around the city in 90F+ ambient temps with the AC running. After idling at the store for 15minutes and then a couple miles of stop and go traffic back to the house, temp gauge on the dash was steadily reading in the normal range.
I plugged in the OBDII reader and saw 205F on the coolant temp. I parked at the house and the temp was staying steady around 200f. IAT reading 165F. I popped the hood, noticed both front E-fans were running high-speed with the mech fan making a pronounced roar if I blip the throttle. Turned off the AC and the temperature quickly went down to 195F and the E-fans turned off. Stayed steady right there, even after turning the AC back on and closing the hood. (FYI only left side E-fan turns on for the AC function. ECM will command both for cooling.)

I'm running an Aisin 180F thermostat, Aisin water pump, and Denso radiator, all replaced within the past few years. Is 200F+ too hot? Is this what is causing my engine to ping?

[98_Q45]

Thanks for responses all. Had written a thoughtful post but then some damn spam Norton thing popped up, ugh (what will it take to get rid of these crazy ads lol)

In short: I changed the radiator, therm and main engine clutch all previously before. Also changed the condenser fan on the left before I realized it probably wasn’t broken, it only comes on during high heat conditions: like coming off the highway with the a/c on. Only 1 condenser fan comes on during light a/c operation.

As for the oil smoke: I did decide to get to replacing the wiring connectors for the VVT solenoids and carefully painted some gasket maker around both tops. Last time I checked it was sealing nicely but haven’t checked again lately since I have to take the V8 cover off. They were leaking and covered in gunk. I couldn’t get the solenoids to budge peacefully, even with deep creep seafoam and a big 26 mm breaker ratchet: so I left them because I didn’t want to risk it breaking and not having any on back up.

I still get smoke though. However I did a ride the other day in 85 degree temps with a/c and some hard throttling: no running hot. I think it only happens when temperatures get above 90-95 with a/c running. When it gets to 100+ degrees, it starts to get wild. Last year when it was 110 on the outside ambient temperature from the pavement, I had to turn the a/c off even on the Highway because the temperature gauge was starting to move past its usual position. If I came to a stop, it would creep up more…but I usually cut a/c and shift to neutral before it gets a chance to overheat. The hotter the engine gets and more idle, the more smoke comes out the exhaust though.

I’m thinking about switching to smokeless oil. Anyone have experience with that? I know it’s pricey though.

[VStar650CL]

If the valve seals are shot (which would be my first guess), you'll see the puffs a lot more when the oil gets hot and thins out. That's simple physics, the seals are basically o-rings that prevent oil from creeping down the shafts of the valves and into the combustion chamber. When the rubber is worn down, surface tension carries oil past it, and thinner oil means more gets through.

If you know you have good airflow through the radiator, then there has to be a coolant flow or efficiency issue. If you're running straight glycol then that's probably your issue, try 50-50 or even 30-70 glycol:water. Glycol is great in winter, but its heat transfer characteristics are garbage compared to water. I should also note that the mixed electric-mechanical fan setup can be problematic in and of itself. The shroud design required by It pretty much guarantees some amount of "parasitic" airflow at all times, so in efficiency terms, it isn't a great setup. In extreme conditions, you may just be seeing the effects of a borderline design.

[fontana dan]

In short: I changed the radiator, therm and main engine clutch all previously before. Also changed the condenser fan on the left before I realized it probably wasn’t broken, it only comes on during high heat conditions: like coming off the highway with the a/c on. Only 1 condenser fan comes on during light a/c operation.

I would double check the operation of the fan clutch. I've had bad luck with replacement fan clutches on this model of car. When i replaced the cooling fan I tried to replace the clutch along with it, but the aftermarket ones were just junk. Poor quality control. I put the original back on and it seems to work fine.

[98_Q45]

If the valve seals are shot (which would be my first guess), you'll see the puffs a lot more when the oil gets hot and thins out. That's simple physics, the seals are basically o-rings that prevent oil from creeping down the shafts of the valves and into the combustion chamber. When the rubber is worn down, surface tension carries oil past it, and thinner oil means more gets through.

If you know you have good airflow through the radiator, then there has to be a coolant flow or efficiency issue. If you're running straight glycol then that's probably your issue, try 50-50 or even 30-70 glycol:water. Glycol is great in winter, but its heat transfer characteristics are garbage compared to water. I should also note that the mixed electric-mechanical fan setup can be problematic in and of itself. The shroud design required by It pretty much guarantees some amount of "parasitic" airflow at all times, so in efficiency terms, it isn't a great setup. In extreme conditions, you may just be seeing the effects of a borderline design.

Thanks, I was thinking the other day if I want to consider replacing the valve seals. Everything is working seamlessly, that’s the only thing that’s an issue. Every long stop light is a puff of smoke and I’m sure it probably isn’t the best look lol. But I’m also considering maybe just an exhaust filter. However I hear they don’t last and only ones I could find only fit single tube exhaust.

But if I can do the valve cover gasket and the valve stems in one job, it might be worth the extra day it takes to do it. I can’t imagine what my cats are like but, I do run the expensive $25 catalytic clean couple times a year at least. Just brought one recently, and I notice more power already.

I’ve not noticed too much issue with aftermarket fans. I just know my original one died hard. It locked up during a road trip, basically staying engaged at all times. Replacement fans seem smaller and lighter weight, but it’s tricky to ensure both belt tensions are right.

I have another V8 vehicle but it doesn’t have a mechanical fan (gotta give it to GM user friendly engineering lol). It also gets better gas mileage on the highway. In some ways I like the silent engine operation without the fan, but having the fan adds an extra pitch without the tacky loud mufflers

[VStar650CL]

Thanks, I was thinking the other day if I want to consider replacing the valve seals.

if I can do the valve cover gasket and the valve stems in one job, it might be worth the extra day it takes to do it.

That's not an option. On an OHC engine you need to remove the camshafts to do the stem seals. It isn't like an old pushrod engine where you can pressurize the cylinders and remove the rockers to knock the keepers off the valve springs. On OHC you're talking about a major teardown.

[98_Q45]

Yikes, sounds like smokeless oil on Amazon might be the better solution lol. Somehow I thought the valve stems just sat at the top somewhere like the injectors (which I’ve previously replaced and wasn’t particularly hard but not fun either lol)