jej3

What is a reasonable variation of temperature on exhaust ports?

If the temperature difference is great, like 200% or more different, what does that mean?

thomasmryan

The last time I had that situation, it was the idle circuit on some 45 DRLA Dellorto carbs. You might do a leak down test on your fuel rail.

jej3

Thanks, @thomasmryan ... So potentially leaky injectors?

jhowell371

Sounds like it to me. Leaky= rich which= lower exhaust gas temperature. YMMV

V2Rocket

what are the conditions when measuring the temps? cold engine, warming up, hot after a 50 mile highway drive...?
using an IR gun or thermocouples in the pipes/ports?

jej3

Hi @V2Rocket - I have a full saga on the engine on another thread. Suffice it to say it is rough idling but runs for a few minutes before measurement. I have measured temps with an IR Gun on the exhaust manifold for each exhaust port.

My 15-year old is out in the garage swapping injectors as we speak from old bosch injectors back to a set of AC Delco injectors which are new.

I'll report back with any updates, soon.

T&T Racing

If the exhaust temperature is 200% lower than the highest, then the lower temperature indicates a lean fuel/air ratio.
What is the exhaust temperature for each cylinder?

jej3

Replaced the injectors and just ran it for about 2 minutes....

Cylinder 1 - 205F
Cylinder 2 - 350F
Cylinder 3 - 150F
Cylinder 4 - 330F

This may sound like a crazy theory but I still am thinking I have some bent valves. I suspect that would provide different fuel/air ratios per cylinder, right?

The engine is otherwise air tight and now correctly timed.

951and944S

What engine is this....?

Easy to tell if valves are bent, especially on the 8V.

T

jej3

It is the 2.5L 8V engine in the 1987 924S

Charlie

Do a compression test and post findings.

thomasmryan

Yep, and throw a vacuum gauge on the intake. Dump some MAP gas or propane around the intake ports.
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T&T Racing

Cylinders 1 and 3 are suspect, can you do a leak down test on those 2 cylindets?

jej3

Hey Everyone -

Did a COLD compression test. I know that's not the way to do it but it didn't seem productive to try to warm up the engine.

Anyhow. Compression readings were:

Cylinder 1 - 0
Cylinder 2 - 95-100
Cylinder 3 - 100
Cylinder 4 - 95-100

Before we undertook the endeavor of turning the car from a beater to a beauty 2 years ago, the engine was running and not smoking nor burning oil.

So, the verdict is BENT valves and she goes in for a TakeLotsOfMyMoney procedure on Monday.

I really appreciate all of the assistance here and my excitement for the final outcome is overshadowing the pain of this process.

I'll report back soon.

thomasmryan

The ol' hobby budget can take a turn sometimes.

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