So yesterday I hit the track. It was doing amazing. S5 jspec, catback, stock dp + cat. Walboro 255. Clutch, flywheel + Pplate upgraded.

It was probably in the mid 90's yesterday too. I kept monitoring the stock temp gauge but it stayed in the middle. Also made sure to open my hood after each 30 min run except the last one.

After the last run, I noticed my coolant overflow was leaking out. So I vented the cap carefully w a rag + she spewed out. I topped her off w some water, then turned it on. Gauge read normal temp. Then I drove home.

Today, I took her out for a drive. It would boost, but not pull at all. I got my delrin motor + trans mounts in today, while I was installing them I noticed a coolant leak around the turbo area. Haven't really inspected it yet though. Then I noticed that I hit 15 psi when I boosted. Still not pulling though. Also I never heard anything pop. It still feels like it has good compression, because down low it still runs well.


Is it overheated? Did I blow a coolant seal?

 

stock cat may be clogged?

 

^ that would totally make sense given what is happening.

 

You can sit here all day and guess, but the only person that can tell what's wrong is you, the owner.

This is the exact reason why they sell and make test equipment. For instance, a compression tester, cooling system pressure tester, leakdown tester and they even make a block tester.

If you don't own these pieces of equipment or do not know how or care to know how they work, bring your car to a professional.

Or you can be like 99.9% of the people that walk this earth and just throw parts at it.

You must be nub if you are tracking your car with cats on it.

 

Do that. It will tell you if you have exhaust gases in your coolant, IE blown water seal. Any general mechanic shop should be able to do this.

 

While I agree with most of what you said about testing systems instead of throwing parts into the car, your last sentence made you sound like a bit of an *******. Nothing wrong with taking your car to a track while street legal. Nothing said about it being a track only car. Sorry to thread jack for a bit.

 

Yeah, that was my first time on the track. I didn't see anything wrong with the setup, but apparently I'm wrong.

How can I test my cat other than taking it off + using a test pipe? Any way to unclog them? Brake parts cleaner maybe?

I'll search about a block tester. Never heard of it before.

 

Off-topic, but one of the requirements for the Street Class in Redline Time Attack is a working catalytic converter.

Running a cat without the air pump, now that's a different story.

 

I bet that low mile j-spec bit the big one.....

 

Compression test without the schrader valve in the bottom showed even pulses of ~93 PSI per rotor face front + back.


Below 3k rpms, it still feels fine + normal. That's why I'm wondering what else it could be.

 

Also, wouldn't I hear a giant POP when it blows?

 

93 is getting to be a little worrying.. Even pulses are good though.

Huh, I wonder if the MAF or pressure sensor came loose... Are you s5 or just s5 keg in s4 shell?

 

91 NA - jspec swap.


So I should plan for a rebuild then yeah?

 

Yeah, I have had 3 J-specs 2 showed up blown, the other was on its last legs...

Plan on a rebuild..... I wonder if the thermosensor is acting up, you can ohm it out to see i it is functioning.

 

I should have added that I bought this from a guy who used it with great success @12 PSI for 3 months.

 

perhaps the turbo is blown....oil in the intake track or IC by any chance?

 

93 psi, even bounces... yeah, motor might be a 'little' tired, but nothing to show the symptoms of what you are seeing.

 

That's a good thought. I'll have to check.


I do know that when I was putting in my motor mounts, water (coolant) was slowly dripping from around that area. I think I said that already too... I'm getting old.


But I'll have to wait till it's not so freaking hot/stagnant out to check things out.

 

If the turbo is blown, you shouldn't be able to make 15 psi. But it's worth a look anyway, since you shouldn't be allowing the turbo to build that much pressure in the first place. Where are you measuring boost pressure? At the turbo, or somewhere on the manifold? If it's at or near the turbo, you could have a big boost leak somewhere between there and the intake ports.

That is if it's not a fried cat or pre-cat. At 15 psi with the stock turbo, your EGTs are pretty damn hot, so it wouldn't surprise me if the element in a cat melted a bit. Pull it out and look through it. If holes are fused together, or there are pieces rattling around, it's done. If so, you can't fix it, so hollow it out in the mean-time and buy a new one.

Only if a seal breaks, dislodges and goes flying through the turbo. Usually it just sounds normal, then is followed by "Oh ****, where'd all the power go?"

 

I'm pretty sure the OP was refering to the bounces being 93psi each, not the total compression of the motor.

When my turbo blew, boost still registered on my gauge (albiet not 15psi worth...which I'm curious as to how your'e accomplishing that on the stock dp) but the power was not there, and it made quite the mess.

 

Hmmm... So basically everything is fine now. I'm really puzzled as to what happened, but I haven't changed a damn thing. My only guess is that the heat from tracking it + outside temp (hottest recorded day in Seattle) messed with something. I do know I have a coolant leak somewhere.

 

Go to advanced auto parts. Rent the pressure tester for the coolant system. It's free and then you will know what's up after that. It will show where your leak is and you will see if the system maintains pressure. Good luck man.