R50/R53 :: Hatch Talk (2002-2006) Cooper (R50) and Cooper S (R53) hatchback discussion.

R50/53 JCW coolant burp and glowing Milltek header

Old Dec 28, 2021 | 05:25 AM
  #1  
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JCW coolant burp and glowing Milltek header

Curious thing I cant figure out. New radiator, pump, and thermostat about 500 miles ago. Reservoir a few months before that. Ever since that it warms up slower than it should and I keep getting air out of the bleed valve. Every once when I do a full throttle pull, it would push coolant out of the reservoir and loose all pressure. Only did it twice so far. It also has a full milltek exhaust with the factory cat. The header will glow before the temperature gauge reaches operating temperature. I can even sit in neutral holding the revs at 3k and it’ll glow. Runs fine, apart from occasionally stalling if I come to a stop in neutral.

The mods are:
17% pulley
RMW246 cam
single mass lightweight flywheel
spec stage one clutch
milltek exhaust
 
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Old Dec 28, 2021 | 06:30 AM
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You have more than one problem. First do a leakdown test and ensure there is no headgasket issue.

For red header I would suspect a air leak on the intake side or blocked cat, what codes are showing?
 
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Old Dec 28, 2021 | 06:40 AM
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The only code showing up currently is for the secondary O2 sensor. Haven’t been able yet to do a leakdown test, but I definitely will do that once I can get ahold of one. I did pump pressure into the cooling system and it seemed fine, but it might not be bad enough for anything to show up at the pressure I put in.
 
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Old Dec 28, 2021 | 06:57 AM
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I had coolant back flow into the reserviour and it ended up being the pressure cap was worn out.
I have new regular exhaust from front to rear and my header glows bright red if I let it sit at an idle. I thought this was normal.
 
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Old Dec 28, 2021 | 08:20 AM
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Originally Posted by Total nutcase
The only code showing up currently is for the secondary O2 sensor. Haven’t been able yet to do a leakdown test, but I definitely will do that once I can get ahold of one. I did pump pressure into the cooling system and it seemed fine, but it might not be bad enough for anything to show up at the pressure I put in.
leakdown with 100 PSI you'll hear where the leak goes if it has one, do it with the rad cap off
 
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Old Dec 28, 2021 | 02:51 PM
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Well, that’s probably my glowing header issue
 
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Old Dec 28, 2021 | 03:59 PM
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Well it actually does still glow with it hooked up. Not as much it seems. Does seem to run better now. But maybe I need to reset adaptions
 
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Old Dec 28, 2021 | 09:47 PM
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Originally Posted by Total nutcase
Well it actually does still glow with it hooked up. Not as much it seems. Does seem to run better now. But maybe I need to reset adaptions
Definitely will need time to re-adapt if the fuel regulator wasn't getting vacuum, it causes a very lean condition. Resetting adaptations without the proper tool won't really do anything, but.... plenty of: Start - Drive - Shutdown, will. (Include all types of driving, City, Hwy & WOT. And leave the Key OFF for at least 5 min before restarting, for the new adapting to take effect, anything less will just use the previous adaptations again.)
Plus if it came off, replace the line or at least the elbow, it's most likely still leaking slightly because of a loose fit or cracks (from drying out because of heat).

Also, secondary O2 sensor code "can" of course be a sign of a plugged CAT.
If you had a boost gauge, higher than normal boost would also tell you (plus it would have warned you about the fuel regulator line being off.)
 

Last edited by BlwnAway; Dec 28, 2021 at 09:56 PM.
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Old Dec 28, 2021 | 09:53 PM
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Originally Posted by ChiefM
I had coolant back flow into the reserviour and it ended up being the pressure cap was worn out.
FYI, this is one of the reasons the factory uses a nylon/plastic coolant reservoir, if the cap goes bad and won't release pressure, the reservoir will let go before the radiator, a much cheaper and easier fix.
 

Last edited by BlwnAway; Dec 28, 2021 at 10:17 PM.
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Old Dec 29, 2021 | 04:18 PM
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Originally Posted by BlwnAway
FYI, this is one of the reasons the factory uses a nylon/plastic coolant reservoir, if the cap goes bad and won't release pressure, the reservoir will let go before the radiator, a much cheaper and easier fix.
Oh, that’s interesting. Did they slightly miss the design mark, or are the failing R53 reservoirs semi-intentional?

By the way, it wouldn’t work that way in Chief’s case since the cap for the R50 is on the thermostat housing and not the reservoir.
 
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Old Dec 29, 2021 | 04:33 PM
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Yeah I see failed reservoirs on volvos that I work on on a daily basis. The plastic just ages over time. Some more than others depending on conditions. And yes the R50 system is similar to the non-euro cars that have a radiator cap, its just on the thermostat instead. I’m not sure the reservoirs on those get pressurised
 
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Old Dec 29, 2021 | 05:01 PM
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Yep, the reservoir on the R50 isn’t pressurized. It just has a simple flip-up cap.
 
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Old Dec 29, 2021 | 08:08 PM
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I will definitely say that replacing that hose would be a huge pain in the ***... Tried to pull mine to test it, and ended up just doing a 'mouth' pressure test. Blocking the other end while blowing in one. Seemed fine and threw it back on. It's snaked under the intake manifold and is a huge pain in the *** to pull out completely. If I ever actually had to, I'd just pull the intake manifold, as it would prob be easier.
 
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Old Dec 29, 2021 | 09:22 PM
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Oops, R50, need to pay a little more attention....
 
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Old Dec 30, 2021 | 04:55 AM
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Originally Posted by BlwnAway
Oops, R50, need to pay a little more attention....
Well, the OP has an R53, so I’d say your comment is relevant. I certainly learned something.
 
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Old Dec 30, 2021 | 05:28 AM
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I did a leakdown test, didn’t show anything obvious. 100lbs in the cylinders and nothing happened in the cooling system. But then I stuck my scope down in there. The first few pictures are stone cold after sitting at least 9 hours. The middle couple are after running a few seconds, the last few are fully warmed up. I think the rings are a bigger issue















 
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Old Dec 31, 2021 | 04:24 PM
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From: OakCreek
Originally Posted by BlwnAway
FYI, this is one of the reasons the factory uses a nylon/plastic coolant reservoir, if the cap goes bad and won't release pressure, the reservoir will let go before the radiator, a much cheaper and easier fix.
No kidding ????? No wonder there's such a high failure rate on the oem coolant reservoirs with them coming apart and leaking at the seam.
 
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Old Dec 31, 2021 | 04:27 PM
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From: OakCreek
Isn't a glowing cat caused by only 1x of 2x things ? Either its clogged or your running extremely lean ?
I would think your few mods alone have the stock injectors at their limit also but they'd still be able to supply enough at idle so that wouldn't cause a red-hot cat.
 
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Old Dec 31, 2021 | 05:55 PM
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Originally Posted by MiniManAdam
Isn't a glowing cat caused by only 1x of 2x things ? Either its clogged or your running extremely lean ?
I would think your few mods alone have the stock injectors at their limit also but they'd still be able to supply enough at idle so that wouldn't cause a red-hot cat.
A cat will glow when it’s extremely rich. But its fine in this case. The header is whats glowing
 
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Old Jan 12, 2022 | 05:19 AM
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The coolant level I noticed does not stay consistent it tends to go up and down some. One time it lost pressure without barfing coolant or steam from the cap. Its a little higher than normal in the reservoir in the picture. This is also right after it barfed. It might be starting to do it more now which means it might be easier to figure out what’s going on
 
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Old Jan 12, 2022 | 08:10 AM
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From: OakCreek
Originally Posted by Total nutcase
A cat will glow when it’s extremely rich. But its fine in this case. The header is whats glowing
I've had a car running too rich and it actually EXPLODED the cat rite out while I was driving , lol that was an interesting one.. do you have an inpa cable by chance ?? If so you can check individual cylinder fueling percentages while it's running and look for variations between cyls.
 
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Old Jan 15, 2022 | 10:55 AM
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Originally Posted by MiniManAdam
I've had a car running too rich and it actually EXPLODED the cat rite out while I was driving , lol that was an interesting one.. do you have an inpa cable by chance ?? If so you can check individual cylinder fueling percentages while it's running and look for variations between cyls.
don’t think I have one of those. The header looks to glow at and right above the collector from what I can see at the top of the wrap
 
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Old Jan 15, 2022 | 11:43 AM
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Originally Posted by Total nutcase
don’t think I have one of those. The header looks to glow at and right above the collector from what I can see at the top of the wrap
This is another sign of a plugged or slightly plugged CAT, the heat will start to build up near the obstruction and work it's way back.
I'd be willing to bet if you disconnected at the CAT, the header would show no signs.
 

Last edited by BlwnAway; Jan 15, 2022 at 03:26 PM.
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Old Jan 15, 2022 | 11:47 AM
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Originally Posted by BlwnAway
This is another sign of a plugged or slightly plugged CAT, the heat will start to build up near the obstruction and work it's way back.
Is be willing to bet if you disconnected at the CAT, the header would show no signs.
hmm. Maybe I should go ahead and try that. Since it’s a Miltek exhaust I have the “test” pipe that I can easily just swap in there
 
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Old Jan 15, 2022 | 11:49 AM
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Originally Posted by Total nutcase
Every once when I do a full throttle pull, it would push coolant out of the reservoir and loose all pressure. Only did it twice so far.
This happened to me as well. Leak down test showed no leaks either. Ended up being the reservoir cap, which of course is what they removed so they could hook up the leak down test.
 
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