Oil pressure fluctuating

[Linville33]

So I bought my 87 V10 SBC 350 in July the oil pressure has always sat around 30 idle to WOT. About 2 weeks ago I start my truck up and it reads 0. It was -20 out and I had to get home from work (didn't have money for a tow) so I risked it. It sounded fine no weird noises or anything. Halfway home oil pressure goes back up to 30. Sometimes at a stop light it would go back down to 0 and bounce up to 30. I stopped by the local parts shop and picked up a can of seafoam poured half of it in the crankcase. Drove the next day with it and changed the oil the next day. That fixed the 0-30 bouncing problem. Now when I start it 45 cold idle. Warms up 30psi, 30 minute drive at 60mph down to roughly 15psi. Truck reads 15xxx but its rolled over at least once. Any help would be great.

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[Boone83K10]

your first indication was that it was 30 psi regardless of idle or WOT. Pressure should go up during acceleration.

you should test the oil pressure switch with an ohmmeter. I don't remember the specific range it should be but higher ohms is lower oil pressure and lower ohms is higher oil pressure.

 

[GTME94]

What weight oil are you running? At -20 the oil starts to get thick like pudding. But also sounds like you might have a pretty loose engine that runs low pressure when warm. Since it's supposed to stay cold I'd look for oil with a big weight spread to not be too viscous when cold but help keep up the pressure when the engine is up to temp.

 

[austinado16]

Start by confirming oil pressure with a mechanical gauge.

Always use a quality filter and never a Fram or other crap filters that fail internally.

 

[Linville33]

I run 10w-30 with a fram filter. Before everyone knocks on fram I have used them for 2 years and haven't bad a problem and my dad has been using them for years and not a single problem. What would you suggest for a mechanical gauge? I'm a college student so money is a little tight

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[IROCmenace]

Get a mechanical gauge from the parts store, like Sunpro or Equus. They are around $20. I have an Autometer but it was $50. Good for engine builds and diagnosis. If you change the in cab gauge to an aftermarket one I would use an electric gauge so you don't have hot oil in the cab with the mechanical gauge. Sucks when oil goes all over your interior. Especially if it is hot.

 

[MrMarty51]

GM used to recommend 10-30 oil, later they changed to 5-30.
The 10 side of the oil would`nt pickup when it was real cold, they was loosing bearings unner warranty and did`nt like that.

 

[Linville33]

Thanks Marty I'll keep that in mind next oil change. I'm not familiar with aftermarket gauges. IROC how would it get in the cab? Isn't it a diaphragm at the block it reads?

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[foamypirate]

Thanks Marty I'll keep that in mind next oil change. I'm not familiar with aftermarket gauges. IROC how would it get in the cab? Isn't it a diaphragm at the block it reads?

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He's talking about a mechanical oil pressure gauge. They are usually fed by a plastic or copper tube, which occasionally will let go. I think early Squares actually used a mechanical pressure gauge, but I can't confirm for sure.

 

[SlickGTP]

He's talking about a mechanical oil pressure gauge. They are usually fed by a plastic or copper tube, which occasionally will let go. I think early Squares actually used a mechanical pressure gauge, but I can't confirm for sure.

They did... My '73 still has the mechanical in it... Copper tube runs through the firewall to the gauge.

 

[Linville33]

Mine is electrical. I know that from when I changed my gauge lights you could pull the gauges right out of the cluster. Mine is a 87. Is there a way I could make a mechanical more reliable as in no chance or slim to burst?

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