Get an unidentified warning beep.

[taeheel2az]

06 225 Optimax
Model 1-225D73FY
SN 1B387675

Happened today after about five minutes at idle. The engine was fully warmed (had made several runs earlier, water temps doing just what they should), WP 2.5 lbs. temp guage 135, good stream from the tell tale. No fault info displayed on Smartcraft monitor. Has happened a couple of times before.

Any ideas? Does compressor overheat throw a fault?

[EuropeanAM]

The BEST means to identify the cause would be to get the engine on the Computer Diagnostic System, for PRINTOUTS of:

-Run History
-Freeze Frame (Fault) History
-Fault Seconds Counters

I'm always happy to review reports by email, if necessary.

Yes, a compressor overheat will result in a fault.

Based solely on your description- I seriously wonder if you don't have one thermostat partially hung open (despite your comments of reaching 135 degrees... one side could be getting quite hot, the other quite cold).

[taeheel2az]

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by EuropeanAM &raquo;</td></tr><tr><td class="quote">. . . I seriously wonder if ... one side could be getting quite hot, the other quite cold).</td></tr></table>

Yep - spot on. Computer diagnostics showed many instances of big difference in t-stat temps, most recent with one t-stat at 135, the other at 102.

I should replace the cold one if I don't find an obvious blockage?

[EuropeanAM]

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by taeheel2az &raquo;</td></tr><tr><td class="quote">

Yep - spot on. Computer diagnostics showed many instances of big difference in t-stat temps, most recent with one t-stat at 135, the other at 102.

I should replace the cold one if I don't find an obvious blockage?</td></tr></table>

Correct.

[taeheel2az]

Debris. Thermostat tested good.

What is the temp shown on the SmartCraft monitor based on? One t-stat sensor? Average of the two?


Modified by taeheel2az at 4:46 PM 2/11/2012

[EuropeanAM]

The temperature displayed on Smartcraft Instruments is a Dampened "Smart" Average of the two cylinder head temp sensors.

There are a few possible scenarios that can actually fall outside the "Smart" capabilities of the PCM, however. One example would be a Port-Side thermostat that's stuck OPEN. This results in lower (but within spec) water pressure.... and the Starboard side's temp climbs higher than normal.

For example- Port side is 98 degrees, Stb side is 151. Smartcraft would likely report a temp in the 135 range (averaging closer to the STB side, as it's closer to the overheating margin).

However.... since the engine is idling, sitting at the dock while you park your trailer/truck for 5 or more minutes- a warning horn sounds, and a "thermostat fault" is set. This is due to the fact that the Port side NEVER REACHED thermostatic temperature range.

The engine is now in Guardian due to the thermostat fault. Now comes the catch: If you turn the key off, and restart the engine, Guardian is no longer active (and would not be, unless the engine idled for 5 minutes, and failed to reach operating temp).

So don't "ignore" warning horns. There are cases where you, as an operator can inadvertantly "over-ride" the safeguards programmed into the PCM to protect the engine. I've seen several cases like this- usually after a massive Cold-Seizure occurred.

[taeheel2az]

Thanks. Out of curiosity, does the Fault Status List in the Service Manual contain all the faults that would be displayed on the monitor?


Modified by taeheel2az at 7:14 AM 2/12/2012

[EuropeanAM]

It may contain the majority of them- but not ALL possible faults are listed.

I've even seen a couple that aren't on ANY list.