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Digital thermometer...what temps am I looking for?

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Mike29

Contributing Member
I just bought a digital thermometer to moniter the temps.on my manifolds and elbows on my 454/350 h.p. crusaders. did a search, but still confused as to what they should be reading. Is 180 at the elbows OK? What about the manifolds? When do I need to be concerned? My boat was a freshwater boat until I purchased it. Now she is in a slip in the salt. Thought I should stay on top of this as a good preventive maint. measure.
 
Mike29 said:
  1. I just bought a digital thermometer to moniter the temps.on my manifolds and elbows on my 454/350 h.p. crusaders. did a search, but still confused as to what they should be reading. Is 180 at the elbows OK?

  2. What about the manifolds?

When do I need to be concerned? My boat was a freshwater boat until I purchased it. Now she is in a slip in the salt. Thought I should stay on top of this as a good preventive maint. measure.
Click to expand...

  1. FYI.... elbows are always sea water cooled.
    IMO, these should run lower than 180* while up and running.

  2. We could use more info.
    Is this engine raw water cooled...... or is it fitted with a close cooling system?
    If closed system, is this a "full system" or is this a "half system"?


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My RWCooled motor runs cooler than yours, about 150 degrees, so my readings are going to be lower.

The manifolds, risers and elbows run about 130 to 140 degrees. (My temp alarms are 160 ' and they never go off.)

Jeff
 
Crusader log style manifolds ...I'm guessing closed cooling half system as the manifolds are in the engine cooling side and elbows are in the seawater side? No risers on this boat. My temp gauge reads right at 150-155 underway which I thought was a little low but found a new 150 deg thermostat on boat so figured must be what previous owner used. Have a LOT of flow out exhaust. Seawater pumps were rebuilt just about 3 months ago. Boat is running great at this time...just want to know what to look out for. Read too many articles about plugged elbows and bent rods etc. on the 454/350 h.p. You guys are very knowledgeable and want to say thanks in advance for this and past answers to questions I've asked. This is our first inboard/slip kept boat and we are lovin it.
 
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Mike29 said:
Crusader log style manifolds ...I'm guessing closed cooling half system as the manifolds are in the engine cooling side and elbows are in the seawater side?
Click to expand...

If your exhaust manifolds are in the "Closed Cooling" loop, then you have what's called a "Full" system.
In which case your manifold temperatures may be warmer than if raw water cooled.
You would be very safe if your actual engine temperature was around 170* to 180*.

Nonetheless, your elbows should remain fairly cool to the touch while up on step.


.
 
Since your engines are running well, you have a great opportunity to record the data now that will help with troubleshooting future problems. Make a diagram of an engine and number the points of interest. Then record for each engine the temps at those points after it is fully warmed up and running. Obvious candidates are exhaust manifolds and elbows (both sides), heat exchanger (all entrance and exit points), temp on the cast iron right next to the temperature sender and the corresponding point on the other side of the engine, temp at the thermostat housing, temp at the oil filter, etc. With that data base for each engine you will be able to quickly find the source of future temperature issues (you will have them at some point). You can also record the list again every season (or every few months) and detect developing problems before they become real issues.

CaboJohn
 
LoL! Thanks guys...that's what I was wondering and now I know I have a full system. Cabo John..great idea! I was going to keep the info in my logbook but a drawing would help immensely.
 
You could also use a permanent marker to mark a few spots (or numbers) on the manifolds, risers (if equiped), and elbows, to aim the temp gun at. This way you will know what areas of the engine the corresponding readings go to. I believe most temp guns should be held fairly close to get an accurate reading because the beam is of a cone shape and not as tight as the light would indicate.
 
Erich's point is worth noting as there are many different brands using almost as many differnet "spot ratios".

to answer your original question - i think 180 deg F at the elbows is way too hot...you should be able to keep your hand on the elbow albeit not for very long (more like 120-130 deg F tops).
 
Agree about Erich's post. It will give a good point to reference. I have not had a chance to measure the temps on the elbows ...I just threw 180 out there but am going to run boat to Newport this Friday so I'll get some numbers then.
 
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