Sudden rise in intake air temperature...

hobieboy · 07-22-2016, 01:13 PM

While on the track last week my pre-intercooler intake air temp suddenly rose by ~50 degF in the afternoon. Even when I was driving home on the highway, the pre-intercooler temperature is still ~30-40 degF higher than I normally see.

When I get home, the rear bumper & the intake side of the intercooler is so hot that I can't even put my hand on it. So I am pretty sure it is sucking in very hot air. And I suspect hot air must be leaking from somewhere.

I look at the exhaust (B&B with heat) and didn't see any cracks. Any suggestion about what else to look?

thanks!

s5uewf · s5uewf's Garage

did your oil and/or engine temp increase, too, or just the intake air temp?

wondering if you have a leak around your tin or if your fan is not moving air and the engine bay air is heating up, which is getting sucked into your intake...?

i would not think it would get that hot, though, ...

mark houghton · 04:27 PM

Running lean perhaps? WUR issues, if you have a WUR still. Or an air leak. You didn't mention if ambient air was a toasty 105 up in Mary-land that day.
Do indeed check the fan belt to make sure it's not slipping and reducing air flow. Good point on the oil temperature to check as well. If the oil thermostat were to stick, your engine block would crank out more heat to atmosphere and raise air temps.

And let's not forget: Measurement devices can go FUBAR sometimes. Perhaps your temperature gauge or sender are acting up. It's like the internet....we trust blindly the info we're fed.

hobieboy · 07-23-2016, 06:26 AM

Oil temp is still very normal... maybe 5 degF hotter. And I am not running lean - ~14.0-14.2 on highway and well into high 11's on the track at high RPM & boost.

No WUR - its EFI'ed

And fan belt was replaced recently. It seems quite tight to me.

What I didn't get was it happened suddenly; on the same day. It was still normal mid morning but temp just jumped since late morning near noon. And even on highway/city driving now, air temp seems higher than before.

My intercooler is big enough to do a fantastic job but it still ends up being 10-15degF higher than before when on track. On a hot day (yesterday which is around high 90's), after 15min driving yesterday on the street, pre-intercooler temp can see as high as 160 degF & I was not on boost much at all but the output remains ~100degF or lower.

gsxrken · gsxrken's Garage

If the fan isn't slipping, and the weatherstripping and the plugs related to the engine tins are in place, your intake air can't be hotter than it was. I can't see how the turbo fan could start thrashing intake air so badly that temps go up even off boost but no other issues (smoke or leaks) coincide with it.
Can you swap the two temp sensors and see if the issue moves to the outlet side?

K24madness · 07-23-2016, 09:23 AM

Pull boot and look at the turbo compressor wheel. It may have some FOD damage. That would explain pre IC temp increases.

T77911S · 07-25-2016, 02:57 AM

where is the temp sensor located? after the turbo but before the IC or before the turbo after the AFM.

check the seals around the engine tin and make sure you are not pulling air from under the car.
make sure seals around the IC and deck lid are good. ( I see a lot of pics here of cars that are not sealed up very good.) this is lost HP.

check belt on fan.

don't want to scare you but possible poor oil flow to the turbo and not cooling it or a problem with oil coolers/Tstats not cooling the oil enough.

RarlyL8 · RarlyL8's Garage

How is the performance? I assume down due to heat but is it way down? If so check your timing, could be stuck.

hobieboy · 07-25-2016, 05:57 AM

I examined both the compressor & turbine - no damages I can find. The temp sensors are at the end tank of the intercooler; before & after.

My concern is my perceived sudden rise in intake temp compared to before - there was no change to engine tin, seals, etc. And I don't recall ever feeling the rear bumper was this hot to touch after 15 min street driving before which point me to think it is the turbo that is building heat.

To check oil flow to the turbo, is it safe to disconnect the supply line for a minute or 2 to measure? What volume should I expect?

hobieboy · 07-25-2016, 06:01 AM

Quote:

Originally Posted by RarlyL8

How is the performance? I assume down due to heat but is it way down? If so check your timing, could be stuck.

Yes, definitely can feel drop in horsepower on the track. But I also retard timing quite aggressively when intake temp is high: on that ~100deg day, running at 1.1 bar I see intake temp @ 123 degF. At ~6000 RPM I pulled timing back to ~15 deg (another 2 deg retard compare to lower air temp). Perhaps I am running too little timing?

Another thought is that perhaps the K27HFS is running out of steam hence pushing temp higher?

T77911S · 07-25-2016, 06:54 AM

oil flow or oil cooling.
check the temp of remote oil coolers.
it could also be the internal oil cooler. if you have good external cooling like me, I have 2, then it could cover up a bad Tstat for the internal cooler.
don't know your setup but you can remove the oil line out of the catch can to check oil flow.
you also want to check the scavenge pump to make sure it is picking up the oil from the turbo

my rear bumper use to get so I could not touch it.
after my turbo rebuild it is much better,

hobieboy · 07-25-2016, 09:20 AM

Quote:

Originally Posted by T77911S

oil flow or oil cooling.
check the temp of remote oil coolers.
it could also be the internal oil cooler. if you have good external cooling like me, I have 2, then it could cover up a bad Tstat for the internal cooler.
don't know your setup but you can remove the oil line out of the catch can to check oil flow.
you also want to check the scavenge pump to make sure it is picking up the oil from the turbo

my rear bumper use to get so I could not touch it.
after my turbo rebuild it is much better,

I mean the oil flow to (for) the turbo.

I have an upgraded external oil cooler as well. My engine oil temp never gets above the top white mark which is ~210 degC I believe even in a hot hot day & long time on the track. In city driving, it barely gets up to the bottom white mark.

smurfbus · 07-25-2016, 10:59 AM

Is it possible your fan ate some blanket or towel? The temp based retard also makes engine run even hotter.

T77911S · 07-26-2016, 03:39 AM

yes
you check that by checking the flow out of the catch can. if no comes OUT of the turbo then no oil is going in.

you also want to check the scavenge pump
You can check flow with a simple test. Remove the line to the scavenge drip tank so that the tank can drain if the engine is running into a big bowel or bucket. Put the line that has been disconnected into the bucket so that it will draw or suck the oil in the bucket out. Watch the amount that is in the bucket. I fit gets higher and higher then the scavenge isn't working properly. But try and prime that line first so that the pump doesn't pump air. The pump should pull good vacuum.

RarlyL8 · RarlyL8's Garage

Inlet temp is 40°F hotter than normal, change was sudden.
Oil temp is not significantly higher than normal.
AFR's are normal.
Performance is down, assumed to be heat related.

If I have these facts correct they point to an issue at the inlet, or possibly a timing issue that occurred immediately. Have you removed the intercooler and inspected? Put the timing back to where it was and tested?

hobieboy · 07-26-2016, 11:43 AM

Quote:

Originally Posted by RarlyL8

Inlet temp is 40°F hotter than normal, change was sudden.
Oil temp is not significantly higher than normal.
AFR's are normal.
Performance is down, assumed to be heat related.

If I have these facts correct they point to an issue at the inlet, or possibly a timing issue that occurred immediately. Have you removed the intercooler and inspected? Put the timing back to where it was and tested?

Yes - these are the facts plus one more: the rear bumper is now too hot to touch after 20min of street driving.

So I also think it points to inlet temperature is too high hence my thought it has to relate to the turbo or muffler.

I didn't change timing - I always programmed the ECU to retard timing more aggressively when intake air temp is extraordinarily high. I can reduce that retardation.

I'll check the scavenge pump & turbo oil supply next. I'll also attempt to check under the (red) engine shroud to see if there's anything blocking but then it does not explain why inlet temperature is high.

RarlyL8 · RarlyL8's Garage

My long distance guess is this is fuel or ignition related. Check the easy stuff first, obstructions in the intercooler or inlet plumbing to the turbo.
Turbo failure is quickly followed by oil in the intake or exhaust or floor. Typically no time to make the bumper hot.
If your AFRs are verified can we assume all 6 injectors are firing correctly?
Verify timing is where you think it is.

T77911S · 07-27-2016, 08:40 AM

oil flow in/out of turbo. that wont make the oil temp go up.
scavenge pump not working like it should will reduce oil flow thru turbo.

timing/AFR's wont effect air temp before it goes into the IC.
sure the exhaust temp can go up heating up the turbo but that would also effect oil temp.
lean mixture will also make engine temps go up effecting oil temp.

it could be the turbo has coking inside it and some has come loose perhaps, reducing oil flow thru the turbo. oil temp would stay the same but turbo temp would go up.

my turbo had lots of coking and the bumper/rear fender was too hot to touch.
after the rebuild it is much cooler

RarlyL8 · RarlyL8's Garage

So many things can cause the engine to run hot. My assumption is that whatever is causing the intake temps to go up is doing this first in the engine which cooks the intercooler. If the oil cooling system is not maxed out it will handle the extra load and temps won't change much. Result is hot intake and exhaust. The turbo can be checked along with the air inlet path.
Where is your air filter located?

hobieboy · 08-03-2016, 04:06 PM

Well, I made some good progress testing where is the hot air come from - built additional tin around the turbo-intercooler inlet connection (I can see the ground looking down so hot air can also come up from the turbo) and it looks like that helped to reduce inlet temp by quite a bit. In the usual 10-15min city drive, temp is reduced by 10-15degF.

But, as I was removing & putting things back together, I made a real bone head move: forgot a rag in the engine bay without knowing. Drove the car. The rag got sucked in by the fan, destroyed the fan belt, pushed my crank sensor out of its mount & looks like I may have even damaged the missing tooth crank wheel

Car had been barely running after I tried to remount the crank sensor & replaced the belt so looks like a lot more things have to come apart now to sort this out before I can go back to look at original problem.

Thanks for the help though guys...