Loss of oil pressure

LtPyro

LtPyro

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So in a nutshell, I built up a Honda j35 block and put it in my car.  I test started the engine and everything seemed fine, so i decided to take it to the dyno to have it tuned.  On the first pass the car lost oil pressure and can't seem to get the pressure above about 15psi even while running the rpms up.  Mine, and the guys at the shop, first thought was a bearing had spun.  I pulled the oil pan off and check all the rod bearings and the main bearings, all of which look perfect.  Other than that what other possibilities am I looking at for loss of oil pressure? 

I installed a new oil pump when I built up the block.  So that is a possibility, but I would like to believe its not.  What else can I check before tearing the engine down to check the oil pump?

 
change the oil filter & see if that does not do it?

Do those motors have spring oil pressure regulators that can jamb up in the hole that it slides in?

is the pressure exactly the same @ idle as when its rev'd up?

Does it have any external cooling/filtering that might have crap in it?

 
Sorry to hear that! Are you using the OEM oil pressure port on the block? 

 
To add: I had a gauge fail: no matter what the sender read, wouldn't read above 10psi.  Was super alarming at first until I shorted the gauge to sender wire to ground and saw it only went to 10 (should peg if it's a 1 wire gauge).  

 
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Bobalos said:
change the oil filter & see if that does not do it?

Do those motors have spring oil pressure regulators that can jamb up in the hole that it slides in?

is the pressure exactly the same @ idle as when its rev'd up?

Does it have any external cooling/filtering that might have crap in it?
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at idle the oil pressure is about 10psi if I remember correctly after it warmed up.  when it was cold before the dyno run it was 65ish I think.

Carwashguru said:
Sorry to hear that! Are you using the OEM oil pressure port on the block? 
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Yes, I did add an oil filter relocation block.  I doubt that would cause the issue since it was holding pressure fine at my house for the 20-30 minutes I had the engine running be fore taking it to the dyno.

Rockwood said:
Verified with another gauge/sender?
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This is a good idea.  I'll verify that my gauge didn't die on me.

 
Second of the huge/sender.  I had a sending unit fail.  Swapped it out. Boom....back in business.

 
Put a manual gauge in the port for the pressure switch.  See what it really is.

 
ive had the senders fail as well when you start it after it sits a while it would read correct and time went on it would slowly loose pressure. the oil was getting on the back side of the diaphragm in the sending unit causing to not to read correctly seen this more than once.   https://static.nhtsa.gov/odi/tsbs/2014/MC-10128532-9999.pdf   this tsb shows the oil pressure relief valve 

 
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I don't know about the Hondas, but years ago I saw this happen to a Ford FE 390 that a guy rebuilt. There is an expansion plug that you need to put in the block right behind the timing gear to close off an oil galley. He didn't know that and so didn't put it in, and had a similar problem (some oil pressure but not much). But I second the idea of temp installing a known good mechanical gauge, hopefully a bad gauge/sender is your whole problem (I've seen many more of those).

 
Ok so after testing it with a mechanical gauge, it seems the engine will only make about 20psi cold at idle.  I will go up a little bit when the rpms come up.  It also has a knocking sound that I think is coming from the passenger side valve cover.  I pulled the cover and double checked all the gaps on the rocker arms to valves and they are all good.

I borrowed a snake camera from a friend and looked into each cylinder on that side and it looks like a little oil is present on top of the pistons.  So I think I'll pull the heads off and check the valve seats.  I had C&G do the heads and thought they checked /replaced all the wearable parts and they installed new valves.

 
Bummer.  Might check to see if the bypass spring flew the coop on the pump and that the screen on the pickup is clear as well.  Fresh motor shouldn't go that low on pressure without associated rod trying to leave noises unless there's a massive leak somewhere.

 
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LtPyro said:
Ok so after testing it with a mechanical gauge, it seems the engine will only make about 20psi cold at idle.  I will go up a little bit when the rpms come up.  It also has a knocking sound that I think is coming from the passenger side valve cover.  I pulled the cover and double checked all the gaps on the rocker arms to valves and they are all good.

I borrowed a snake camera from a friend and looked into each cylinder on that side and it looks like a little oil is present on top of the pistons.  So I think I'll pull the heads off and check the valve seats.  I had C&G do the heads and thought they checked /replaced all the wearable parts and they installed new valves.
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how is checking valve seat going to tell you why theres oil on the pistons? and how would they contribute to your oil psi issue?

 
Ok I had to take the heads off to see this one.  Not sure how this causes oil pressure to drop or if it even does cause it.  Looks like the wrist pin clip came out.  So either I forgot one (possible but I kinda doubt it) or maybe the groove wasn’t deep enough to hold it in.  Either way it’s deep enough to toss this block and start another or bite it out and get new pistons.

76819D7D-539E-456F-B81D-D92811700040.jpeg

 
Yep get another block and maybe your piston isn’t damaged as it’s on the side but if the rings don’t spin perfectly then the ring lands were damaged too. C clips never fall out when installed properly. 

 
I don’t see how this would affect your oil pressure, thinking you still have some unresolved issue.  Sucks to see that cylinder on a new engine

 
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