Head gasket ECU indicators

[bigstrusk]

I've recently diagnosed a bad head gasket on my 2011 2.5i via CO2 test of the cooling system, likely an internal failure. I know the HG will need to eventually be replaced. I'm getting quotes now, but I need to wait a while to cover the $.

At the moment, the system can still regulate itself provided the coolant is full, with coolant temps averaging 190 and max at 215 (hot day idling after a drive). I believe the "warning" point is ~230 and "uh oh" point is ~240.

I know to keep my eyes out for the physical signs like white exhaust smoke, mixed fluids, and external leaks (which I have none of atm). I have my Tactrix hooked up to BtSsm so can monitor most things ECU-related. I've tuned my throttle but haven't yet learned the guts of engine tuning.

What are the important parameters and thresholds to pay attention to that would indicate the problem is getting worse?

Edited August 9, 2023 by bigstrusk

[Max Capacity]

It's a 2.5i so there's not a lot you can do performance wise. Just keep up with normal maintenance. 

 

I wonder what condition the coolant is in, has it been replaced ? When the HG is replaced, I assume by a indi shop not a dealership, they will replace the coolant, maybe have the coolant system pressure tested too.

 

I'll assume there is a timing belt, has that ever been replaced, again, when the heads are off, it should be replaced. I'm not really up on 2.5i's

[bigstrusk]

Thanks for the reply! I'm not looking to tune the engine really, just what ECU params would show a worsening HG. Ex) would I see cyl roughness increase? Misfire codes? Will knock or IAM get increasingly worse? Wasn't sure if anyone out there had any experience on what typically goes wrong first. 

All routine maintenance and troubleshooting has been done. Changed TB, water pump, and coolant 20k ago, which was ahead of schedule. I'd more recently pressure tested the system as well; maybe I'll static test it again for hahas, but pretty sure that since it's an internal leak, a running test would spike up. 

[Max Capacity]

If you have the MLS HG installed you should be fine. Seems the fix for the old HG issues in the 2.5i was to use the MLS HG the turbo engine got.

[KZJonny]

I'd be genuinely curious to hear what the quotes you get for the work might be.

I just did this job on my 2.5i, and aside from the fact that I already own an engine hoist and stand, which I recognize are costly, it wasn't so bad. I got a complete head gasket job set for maybe $240 CAD, which had more gaskets than I really needed/was going to swap, so I could've gone cheaper there and just got intake/exhaust and head gaskets.

Fresh fluids new timing belt and some exhaust studs + shop materials... I'd say I'm less than $500 CAD into it? So, that could either be incentive to have a go yourself, or at least a comparison to what someone might charge you.

If you take the heads to a machine shop, you'd need to factor that in as well, but any garage would pass that cost on to you as well, so it's kind of a wash on that one....

Edited August 9, 2023 by KZJonny

[bigstrusk]

On 8/9/2023 at 9:20 AM, Max Capacity said:

If you have the MLS HG installed you should be fine. Seems the fix for the old HG issues in the 2.5i was to use the MLS HG the turbo engine got.

I believe I do (MY11) and unfortunately I am not, verified by combustion leak test and bouts of overheating. 

On 8/9/2023 at 11:38 AM, KZJonny said:

I'd be genuinely curious to hear what the quotes you get for the work might be.

I just did this job on my 2.5i, and aside from the fact that I already own an engine hoist and stand, which I recognize are costly, it wasn't so bad. I got a complete head gasket job set for maybe $240 CAD, which had more gaskets than I really needed/was going to swap, so I could've gone cheaper there and just got intake/exhaust and head gaskets.

Fresh fluids new timing belt and some exhaust studs + shop materials... I'd say I'm less than $500 CAD into it? So, that could either be incentive to have a go yourself, or at least a comparison to what someone might charge you.

If you take the heads to a machine shop, you'd need to factor that in as well, but any garage would pass that cost on to you as well, so it's kind of a wash on that one....

Dealer quotes are 3500+, not including any extras or machining. Indy/specialists around me are ~3000 including extras and machining. $USD 

I am mechanically and technically competent enough to do the job myself. However, family, work, and the other 2 car projects I've got mean I've gotta outsource this one because of time. 

Edited August 18, 2023 by bigstrusk

[bigstrusk]

Theorizing here: HG internal leak means compression should be low somewhere right (on my list to verify). That would be misfires, correct, but anything else? Would that also mean a richer AFR? And then by extension, I would *not* expect more knocking, measured by FLKC, low IAM, LV,.. because those are lean indicators? 

I'm absolutely not an expert on how these ECUs behave... this is where I need help. 

Edited August 18, 2023 by bigstrusk

[m sprank]

Can't say I ever caught a head gasket leak in a log.  Even on the dyno.  If the HG was suspect we tested physically, not digitally.  Once you know its popped you stop.  It will only get worse and cause more damage.  The engines are expensive enough already.  $3k is about normal for a HG replacement with resurfacing of the heads and new valve seals (N/A car).