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ahays
08-30-2007, 12:38 AM
My local Mastercraft dealer sold me an undersized water pump for my '87 Tristar 351 last summer and I overheated at full throttle. I changed the oil at the end of the season with 5 qts. of Castrol HD 30. The engine sounds and runs normal except that the oil pressure reads low once warmed up. When cold it reads 60 psi, after the initial warm up it is at 40psi but with more running it drops to 25-30 psi. At idle it drops into the 5-15 psi range. The water temperature reads in the 155F range as it always has.

I just want to confirm that the proper procedure for troubleshooting this is as follows:
1. Confirm that the oil level is proper.
2. Check the sending unit (how is this done? by using an oil pressure gauge to compare to?)
3. Replace the oil filter in case it's clogged.
4. Drop the oil pan and check the oil pump pickup for debris
5. Remove the pump and inspect the clearances and look for damage.
6. Measure the rod and main bearing clearances (do I use that plastic gauge material for this?)
7. Anything else? I saw somewhere that people were suggesting pulling the valve cover off and look for oil being pumped to the head. Where does this fit into the troubleshooting process?

Thanks,
Andy Hays
Keuka Lake, NY

Jesus_Freak
08-30-2007, 04:58 AM
Welcome!

What kind of oil did you normally use before the HD30? 10/40 and 20/50 would both have produced more pressure at operating temp than HD 30. Have you searched this forum? Many oil pressure discussions have taken place, and others know much more than I.

ahays
08-30-2007, 07:58 AM
Welcome!

What kind of oil did you normally use before the HD30? 10/40 and 20/50 would both have produced more pressure at operating temp than HD 30. Have you searched this forum? Many oil pressure discussions have taken place, and others know much more than I.

I've always used the straight 30. The forum does have a bunch of oil pressure discussions as well as the automotive forums which is how I developed the consolidated list of bits and pieces. I'm just trying to make sure the list is complete and find out if there is anything else that might be relevant for an '87 Indmar 351.

Jesus_Freak
08-31-2007, 05:02 AM
I've always used the straight 30. The forum does have a bunch of oil pressure discussions as well as the automotive forums which is how I developed the consolidated list of bits and pieces. I'm just trying to make sure the list is complete and find out if there is anything else that might be relevant for an '87 Indmar 351.

Sounds good. Not everyone searches first, so I was just asking. I hope someone chimes in with suggestions or additions to your list, if any.

pkskier
08-31-2007, 10:19 AM
I have an '87 TriStar also and my oil pressure would react very similar to what you are describing. A friend who is a mechanic suggested that I use a 20/50 oil since the problem was only occuring after running the engine for a while. Switch to the 20/50 and have not had a problem since.

JimN
08-31-2007, 10:57 AM
Remove the oil pressure sender and see if it's clogged. Someone used Teflon tape to seal theirs and it went past the end of the thread, so it eventually flopped over and covered the hole on the sensor.

ahays
09-04-2007, 07:45 PM
Whew! Thanks for the help guys. I went out and bought a manual oil pressure gauge from the auto store and have confirmed that the sending unit or dashboard gauge is the problem. I am running around 55 psi normally with it dropping down to 30psi in idle after running it hard. It looks like I should be back in business with a $30 outlay.