How to diagnose stetching headbolts?

[ricekikr]

How exactly do you diagnose stretching headbolts? I've been having issues with high coolant pressure causing flange cracking both times happening at 35psi around 6.5krpm. Sensor pops out then loses all coolant.

Just did a comp test now, 170across.

One diagnostic i'm thinking of is running low boost (driving like i used to with high boost) for a month or so and see if the flange cracks again.

No mayo oil
No overheat
Smooth idle
No apparent power loss when driving normally
Plugs look exactly like they did pre-issues (blackish not white like most headgasket issues)

Loss of hp at highboost based on hp calculation (time, gear ratio, weight, cd etc etc), compared to previous logs. The maths were pretty consistent. Log to log, it shows 100whp loss, specifically when it reaches max boost. (Ie the logs show power dropping as soon as i reach peak boost and rpm increases)

Only other symptom is coolant leak where the cts mounts (usually right before the part that holds the sensor cracks)

[viceprp]

what coolant flange are you buying? I heard of them cracking on cheap flanges.

were the runs recent?

[viceprp]

Need a quick rundown of your car.

[ricekikr]

Latest high hp run is a couple months old. I doubt its the turbo since its relatively new, no erosion or play on both sides.

Just for info the previous turbo (5857) logs were within a 10 hp of each other, these were 50+ logs so i'd say pretty consistent.

Last flange that cracked was supposedly oem but the part numbers looked off, (lighter than what i was expecting), next was a cheap dorman. With the Dorman, plug and sensor were ziptied since new. Cracked both sensor and plug locks at the same time.

Aeb
stock piston
Elring head gasket (checked rpurchase record, thought i had reinz)
Audi bolts
Hx35 35psi (sometimes a jumps a bit higher if i start at low rpm in 4th+ gear then ignition retard as overboost protect)
Scat rods
~7800rpm on 1st then 6500-7000 2nd-6th
Forgot the waterpump brand, from ecs, metal blades.


Just tried a couple 15psi runs 6000rpm + ~45min driving around at 3k 2nd and 3rd gear, on the cracked dorman flange with the sensor and plug ziptied. No coolant loss, no misfire, and the sensor stayed in place.

[ricekikr]

what coolant flange are you buying? I heard of them cracking on cheap flanges.
?

My initial plan to get an oem flange from a reputable shop. And go from there.

[ricekikr]

Another question? Will a blown headgasket make the little cola sized bubbles? Thats how i check with a normal cap on radiator, thought might be different for expansion tank type.

Don't have bubbles on the expansion.

[seanf86]

have you pressure tested your coolant cap? maybe the bypass isnt releasing excess pressure

[ricekikr]

Drove it again 2hrs this time mostly stop and go. A couple short burst 2nd/3rd gear 15psi 6k. Still no coolant loss or cts popping out.

If i try a 35psi run and sensor pops out is that a very good sign of stretching headbolts? Cant understand why it wouldn't damage the gasket when it stretches if it is indeed headbolt stretch. Cause it seems to be working fine right now.

Another, the temp should rise before anything blows if i'm overheating right? Temp has never risen past half (always just left of half), even when low coolant pops up but i do stop immediately and refill.

[ricekikr]

have you pressure tested your coolant cap? maybe the bypass isnt releasing excess pressure

Seerlah said the cap doesn't have a pressure release like a normal radiator cap. Which is it?

I mean most if not all cars that have a rad cap has a pressure release on it. I was wondering why ours didn't. Always thought the little holes on the cap was the release.

[seanf86]

it must have a bypass, try changing your cap for shits and giggles, they are cheap anyways.

[ricekikr]

it must have a bypass, try changing your cap for shits and giggles, they are cheap anyways.

Exactly. Will do that. I still have my old cap, just need to find it.

Just talked to a friend, his cap was too soft, releasing pressure all the time. So the cap must have a release of sorts, unless his cap just wasn't sealing.

[GrapeBandit]

Hx35 35psi

off topic: what turbine housing are you running? Holset? what turbo manifold?

[ricekikr]

Cap does have a release

[Seerlah]

I had my tank pop before. My cap also does not look like that.I learned about the overflow from personal experience and bleeding it.

[ricekikr]

off topic: what turbine housing are you running? Holset? what turbo manifold?

Timsturbo .63. Atp clone, fits almost as tight as a 5857. Replied on your thread lol.

The timturbo .63 is significantly smaller than the pte .64. Both inside (using the scientific method of seeing how deep my finger went) and outside. Looks a little bigger than a 50trim .48. The .64 is significantly larger. Upside is spool is a bit better than the 5857 and based on calculations made the same hp as 5857.

There are a couple threads saying that the timsturbo .63 is closer to a bep .55 than a garett .63

[GrapeBandit]

Timsturbo .63. Atp clone, fits almost as tight as a 5857. Replied on your thread lol.

The timturbo .63 is significantly smaller than the pte .64. Both inside (using the scientific method of seeing how deep my finger went) and outside. Looks a little bigger than a 50trim .48. The .64 is significantly larger. Upside is spool is a bit better than the 5857 and based on calculations made the same hp as 5857.

There are a couple threads saying that the timsturbo .63 is closer to a bep .55 than a garett .63

sorry man, I must have read right past your reply in my thread. I heard a lot of bad tbing about the tims turbo turbine housings, that they were indeed smaller than advertised. instead of a thread jack, im going to shoot you a PM

[ricekikr]

I had my tank pop before. My cap also does not look like that.

Ah that's why. Weird thing is my cap can be pushed by hand, no where near stuck. The pressure must release thru there before flange explodes or why on my 2nd exploding flange, both sensor and plug exploded. Must just be crappy flanges. And if I put water on the holes it'l hold it, but once I push down on the holes, the water falls immediately. So it must hold pressure (exploding flange) and releases it an unknown pressure (it does feel like it's around the same spring rate as a 1-1.3bar rad cap)

[S4NIK8]

Only thing I have to offer is that I have seen 1.8 blocks with very fine cracks in the cylinder before causing similar problems. Low boost no problems - High boost and would explode coolant flanges.

[ricekikr]

Only thing I have to offer is that I have seen 1.8 blocks with very fine cracks in the cylinder before causing similar problems. Low boost no problems - High boost and would explode coolant flanges.

overbore fix it?

[S4NIK8]

overbore fix it?

re-block was required, there were cracks leading from the cylinder bore into the coolant passages. Not saying this is your issue, you could always crank the boost back up and run it until the specific failure makes itself more visible.

[ricekikr]

re-block was required, there were cracks leading from the cylinder bore into the coolant passages. Not saying this is your issue, you could always crank the boost back up and run it until the specific failure makes itself more visible.

Ahh that sort of crack I was thinking more of the common hairlines on the bore type. But yeah thorough inspection is needed.

[viceprp]

Stretched bolts would give you milky oil.

[ricekikr]

Stretched bolts would give you milky oil.

And a cracked bore would overheat all the time right?

[redline380]

Why don't you at least pressure test the cooling system?

[ricekikr]

Why don't you at least pressure test the cooling system?

Just cause it doesn't overheat/lose coolant or pop the sensors in low boost. If there was a headgasket leak it would pressurize it more than what my compressor could (forget at what psi the compressor turns off).

But yeah, I should do that.

[redline380]

Just cause it doesn't overheat/lose coolant or pop the sensors in low boost. If there was a headgasket leak it would pressurize it more than what my compressor could (forget at what psi the compressor turns off).

But yeah, I should do that.

Considering it will tell you if you have a cooling leak, yeah, I would do it

[viceprp]

If you have a cracked bore, which takes a lot, you will see puddLing on the pistons or leaking to the oil or signs on the spark plugs. Depending where it's cracked. This would cause misfires on start up and rough idle til the coolant is burned.

OEM coolant tank cap and coolant flange is a cheap parts list to start with.

Is this a DD? If it were me, I would take the head off and get that pressure tested. Inspected the head bolts. You will literally see the hour glass shape if the bolts are stretched.

The more I think about it, the more my mind wanders for the worse. Stick to the basics first.

[S4NIK8]

If you have a cracked bore, which takes a lot, you will see puddLing on the pistons or leaking to the oil or signs on the spark plugs. Depending where it's cracked. This would cause misfires on start up and rough idle til the coolant is burned.

OEM coolant tank cap and coolant flange is a cheap parts list to start with.

Is this a DD? If it were me, I would take the head off and get that pressure tested. Inspected the head bolts. You will literally see the hour glass shape if the bolts are stretched.

The more I think about it, the more my mind wanders for the worse. Stick to the basics first.

Not saying the 1.8 blocks are weak, the one I have seen with a cracked sleeve was a fairly mild build.

Back on topic - http://www.napaonline.com/Catalog/Ca...006_0361073538 Go buy that and try it before you bother taking the engine apart.

[viceprp]

There are no sleeves. I've hear of cracking a block in half but that was an 058 making 800+whp

[ricekikr]

Not daily driver, but drive it whenever I'm going on a freeway.

The power part of the problem was solved. Just replaced the plugs (larger .034 gap compared to my usual .026), changed dwell setting on the stock ecu (for the fsi coils - these are same coils). Ran like butter, made significantly more power at 27psi vs 35psi when I started this thread.

It didn't occur to me that the plugs could've fouled again, and like last time they still looked very useable (no erosion on the tips and dry dark brown/black).This time less than 1k miles.

Before this thread, i haven't read about exploding flanges, just warping. And it had a bit of trouble starting right after the flange broke. But after leaving it overnight, started one-click. And cmon <1k miles (literally just a couple days driving old), I used to get 2-3k miles (hopefully the new dwell settings fixes that).

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The ziptied (still on cracked flange) sensor was holding up fine even up to 30psi. But not continuous runs, just 1-2 shift or 2-3 then cruise, with the fouled plugs.

After changing plugs did a a couple 1-3rd short shifting 4th gear runs, only stopping to check logs. 27 then 30psi, the ziptie stretched a bit the sensor unseated and let the water out.


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Oem flange will be ordered in a few day (Ecstuning this time). Hopefully it lasts longer.