Radiator Cap

[JLR]

Shooting the breeze with my DD mechanic. He said my 1292ddec's should be using a 16 lb radiator cap. The ones on now are Detroit Diesel 7 lb caps. Does anyone know the part number for the DD 16 lb caps or a source for them? Thanks.

 

[Fanfare]

Depends on your engine. The 92 series have o ring seals and require the 7 lb caps.

 

[JLR]

I guess the DD mechanic was mistaken? He said they should be 16lb caps to raise the pressure to prevent bubbles?

 

[JLR]

Does anyone know for sure what the correct pressure cap is for a 1292 DDEC?

 

[captddis]

12 and 16V92 DDEC require a 15 lb cap.

 

[Salty Dame]

Two weeks ago this very subject came up in regards to my bosses engines. 12V92 DDEC. Z54 Donzi. I called Pacific power products in Seattle and they said the seven pound cap (the one installed)was right. On Thursday the boss calls me and says he has coolant and steam coming out the exhaust and a loss of power. This doesn't look good. I just checked and it looks like the coolant drained to the sump. Busted liner? I sure hope this teardown isn't because of a ten dollar cap.

 

[JLR]

Still confused.

 

[captddis]

Still confused.

So your mechanic and I both gave you basically
the same answer and you are still confused?

How many answers do you need?

 

[JLR]

That's kind of an interesting tone. I ran 1100 miles plus using a 7lb cap without a problem, and presumably the previous 2200 hours on these engines as well. Before I violate the if it ain't broke, don't fix it rule, I'd like to be sure that making the change will not negatively impact these motors. If that's problematic for you -- well --fill in the rest.

 

[Plan B2]

I am definately no marine Diesel expert so take my .02 for what it is worth.
I have seen a non marine engine overheat because the cap was defective. The coolant boiled/ cavitated and could not transfer enough heat from the engine block. A New cap of the appropriate pressure no more over heating issue.
As pressure increases so does the boiling point of water, therefore with a higher pressure cap you get less "bubbles" that translates to less cavitation within the cooling systems. If you have a poor mixture or some other issue that was causing a boil over, increasing the presure at the cap might get you by until you con complete further diagnistics checks, but you run the risk of blowing our some other component.

I' know this doesn't tell you what PSI to run, but I would stick with the 7 lbs. unless you are experiencing a problem with the cooling system overall.

 

[JLR]

Thanks. I am not experiencing any problems. I imagine that switching to a higher pressure cap might put higher pressure on some seals or other components and do not want to run that risk unless there is a reason to do so. That is it in a nutshell.

 

[captddis]

That's kind of an interesting tone. I ran 1100 miles plus using a 7lb cap without a problem, and presumably the previous 2200 hours on these engines as well. Before I violate the if it ain't broke, don't fix it rule, I'd like to be sure that making the change will not negatively impact these motors. If that's problematic for you -- well --fill in the rest.

Ok I will fill in the rest. Don't waste time on those who just like to ask questions and don't want answers.

 

[Boatsb]

That's kind of an interesting tone. I ran 1100 miles plus using a 7lb cap without a problem, and presumably the previous 2200 hours on these engines as well. Before I violate the if it ain't broke, don't fix it rule, I'd like to be sure that making the change will not negatively impact these motors. If that's problematic for you -- well --fill in the rest.

I wouldn't trust Dave at all. He is one of the busiest and we'll respected Detroit mechanics in his area and probably is in such demand because he is always doing things wrong.

You could call your local Detroit distributor with your serial numbers and get the info on the original build of that motor and see what they used. Check all the service bulletins and updates to see it there are changes and then you'll know.

 

[Avenger]

Don't sweat it Dave. My wife does this to me all the time. She doesn't really want the right answer, she just wants affirmation of her opinion.

Now, in relation to the question; In accident investigation they refer to "Normalization of risk." It's the practice of doing something dangerous, but not recognizing it's dangerous because it hasn't jumped up and bit you - yet. Essentially the same thing as "If it ain't broke don't fix it."

Sometimes you have to fix the 'ain't broke' so it stays 'ain't broke.'