Loss of oil pressure. Whats going on?

[beyondloadedSE]

Alright, when I first installed my engine, my engine was reading about 75 psi of oil pressure upon cold start up and about 25 psi when warmed up. My autometer oil pressure guage is tapped in the head FWIW. Well, now for the last few months, my oil pressure light has been flickering at idle once the engine has been warmed up. It's not the stock oil pressure sending unit, because now my autometer oil pressure gauge at idle reads slightly over 50 psi upon cold start up and about 5 psi once warmed up. Ive talked with Rick and we both agree that if it were the pump, it would most likely be either working or not working and nothing in between. Could some crap in the oil pickup screen be stuck and cause this much of a pressure drop? Any other ideas of what could cause this? I feel likes its just a matter of time before I spin a bearing.

[Pale Horse]

Something that IceFury and I found was that during his engine assembly, the builder used RTV black as a gasket sealer for the Oil pan (to aid in sealing, not the sole provider of seal). It had also been used around the timing cover. The problem with this is when the RTV sees the heat of the Duratec, it becomes brittle. The pieces then fall into the timing cover and pan. When we dropped the pan on IceFury's car, the pick-up tube had a ton of the RTV blocking the screen. This could be what has happened. All you will have to do is pull the pan and inspect it. I'm not sure where you tapped the head for pressure signal, but surely Rick has either given it the thumbs up or nay sayed it. You might PM some more of the F.I. guys and see what they say about your sender location.

[beyondloadedSE]

All you will have to do is pull the pan and inspect it.

Unfortuantely, I wish it was that easy. One of my turbo exhaust manifolds runs underneath the oil pan and its going to be a huge job to uninstall. But from what I remember, RTV silicone was used for the oil pan gasket. Perhaps this is the culprit.

[Buckshot77]

I too have seen the RTV issue clog up a pickup screen from another engine I disassembled that was originally built by someone else. It's possible that this is the case on this engine as well, but I'm usually pretty careful about not using excessive amounts of RTV which is typically what causes that. A small 1/4" or less dot of silicone at the spots shown in the rebuild drawings will do a fine job of sealing those areas along with the actual seal. The main area I've seen excessive use is at the separation area of the block where RTV is the only sealant used. Also, FYI, I use a high temp RTV to avoid issues with excessive heat that the duratec seems to create.

My other thought on this issue is the recurring issue of sand in the block left from the original casting. I ran across this on my personal motor when I pulled the plug in the end of one of the oil passages in the heads. There was casting sand actually piled up in the end of the passage approximately 1/8"+ thick. Of course this is the typical location for a pressure sending unit to be mounted and could definitely screw with pressure readings if some grains of sand got lodged into the inlet for the sending unit.

I too would like to hear some additional comments on this. Unfortunately, I think the best and first route to go is pulling the pan as well.

Rick

[warmonger]

I too have seen the RTV issue clog up a pickup screen from another engine I disassembled that was originally built by someone else. It's possible that this is the case on this engine as well, but I'm usually pretty careful about not using excessive amounts of RTV which is typically what causes that. A small 1/4" or less dot of silicone at the spots shown in the rebuild drawings will do a fine job of sealing those areas along with the actual seal. The main area I've seen excessive use is at the separation area of the block where RTV is the only sealant used. Also, FYI, I use a high temp RTV to avoid issues with excessive heat that the duratec seems to create.

My other thought on this issue is the recurring issue of sand in the block left from the original casting. I ran across this on my personal motor when I pulled the plug in the end of one of the oil passages in the heads. There was casting sand actually piled up in the end of the passage approximately 1/8"+ thick. Of course this is the typical location for a pressure sending unit to be mounted and could definitely screw with pressure readings if some grains of sand got lodged into the inlet for the sending unit.

I too would like to hear some additional comments on this. Unfortunately, I think the best and first route to go is pulling the pan as well.

Rick

I've found that almost all of the silicone sealants work well and do not get brittle under engine heat. The factory sealant is similar to Ultra-Black RTV and even it does come off in chunks from where the block skirt is sealed. This is because it is then right where it oozes out from being clamped and tends to fall off and drop in the pan.

Using excessive RTV causes this in any case using any kind.

The trick I've found is to apply your Ultra-Black RTV to your sealing surface, then stick the gasket to it and lightly apply the other mating surface. I usually will wait several hours if not overnight and then go back in the next day and torque everything. Mainly in the case of the timing cover the sealant goes on the block where the seams are. THe gaskets are in the timing cover. I apply the sealant and push the cover in place, thread in all the bolts and then tighten about 1/4 turn to even out the cover and sink it into the sealant beads. Then after it does some curing I torque to spec.

This procedure allows the sealant to stick to the gasket and the surface but not be squished out everywhere and form globs that break off into the pan or chains. Then it actually becomes part of a compressible gasket so that when you torque it down it has some compression on it and seals any irregularities in the surface even better.

[beyondloadedSE]

thanks for the input guys. Just looks like I need some time to pull the oil pan now.

[Big Jim]

Another perspective from general terms, not Duratec specific.

Oil pressure will be higher when cold. It is normal. The oil is much thicker. You may want to check and see which oil you are using. Extremly high cold pressure can be from using an oil that is too thick. You should be using a 5WXX (factory recommendation when new was 5W30). If you are using 15W40 or 20W50, that engine doesn't like it. Even 10W30 or 10W40 is iffy.

Next, low oil pressure when warm is often due to worn bearings ON MOST ENGINES (not Duratec specific). Especially the main bearings. They allow too much leakage, dropping pressure. IN GENERAL TERMS (not Duratec specific) a clogged pick up screen will cause low pressure when cold as well.

Keep an open mind as you look further into this.

[stilov]

Unfortuantely, I wish it was that easy. One of my turbo exhaust manifolds runs underneath the oil pan and its going to be a huge job to uninstall. But from what I remember, RTV silicone was used for the oil pan gasket. Perhaps this is the culprit.

that sucks man...my turbo kit allows access to the pan.

I will be interested to see how this unfolds.

[ContourGuy9817]

i am tapped into the heads. i have a reading of 80+ at idle on cold. 13 psi at 30 degress and above when warm. below that temp it can get up to 22 at idle. 5w20 mobil-1. also, i would recommend pulling the pan and checkin your input screen.

[ContourGuy9817]

also a fair judgement is 10 psi for every 1000 rpm for proper oiling capabilities.