Oil sender conundrum

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Julian
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Oil sender conundrum

Post by Julian »

Over the years the Oil gauge in my Interceptor has always appeared to read a little low - not catastrophically but below 50 (it's a low mileage engine built by Hauser Racing).

At one stage I had it checked and was told the pressure was indeed higher than indicated, right where it should be.

That left me wondering if perhaps the sender was the wrong one and an idle moment I ordered a new sender from Robeys and yesterday fitted it without too much drama - just skin loss. It matches the one that was installed, right down to the markings, #'s etc on it.

I then started the car and the pressure climbed nicely ... and kept climbing, hitting 100 and sitting there, not dropping as it warmed up. What the @#$% ?

I doubt very much that it is that high in real life as the engine runs fine, doesn't use oil etc and with the oil sender read lower :)

So other than a dud sender, unfortunate in return terms as I'm in NZ ... any other thoughts from any one why this could be?

All other electrics etc work fine, always have - still do. Thanks J
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Chris_R
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Re: Oil sender conundrum

Post by Chris_R »

The original senders were made by Smiths uniquely for the Jensen Interceptor to match the Jaeger gauge. They were also later fitted to the Lotus Europa with the Renault engine. If your sender and gauge do not match you will not get a proper reading. A picture of the back of the sender you have may help.
You may find your answer in this thread: viewtopic.php?t=33028
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Julian
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Re: Oil sender conundrum

Post by Julian »

So .... I received a second sender from Robeys, same result near 100.

Next step was connect a mechanical gauge. 85 psi, not much drop when hot.

Googling hasn't helped - tho a number of posts suggests 85 isn't an issue ... thoi most posit considerably lower pressure as "normal"or "right".

I've had the car since 2007 and done reasonable miles in it without apparent ill affect. I guess "don't; touch what's not broken".
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Re: Oil sender conundrum

Post by Chris_R »

It is difficult to know what is going on here. A reading on the mechanical gauge of 85psi cold and also when hot is really quite odd. The viscosity of oil decreases very significantly as it gets hot and as a result flows much more easily with much less resistance which is why normally you do observe a drop off in pressure reading as the engine heats up and the oil gets hot. I would expect to see that reading drop off quite significantly when the oil has warmed up. It seems to indicate that the pump is pushing (attempting to push) more oil into the system than the system is capable of passing through.
This diagram indicates how viscosity changes with temperature:
Viscosity vs Temperature.jpg
Viscosity vs Temperature.jpg (54.71 KiB) Viewed 552 times
The original specification for the Chrysler engine was for an SAE40 grade of oil when hot which has a hot viscosity of between 12.5 and 16.3 so the engine was designed with that in mind. If you have a SAE50 weight that has a range between 16.3 and 21.9. Compare that with the values at lower temperatures.
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Julian
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Re: Oil sender conundrum

Post by Julian »

thanks Chris. I’m back in the US for a few weeks and will investigate further once home.
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Grant
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Re: Oil sender conundrum

Post by Grant »

Julian wrote: Thu Jun 08, 2023 7:17 pm thanks Chris. I’m back in the US for a few weeks and will investigate further once home.
Julian..There's is Nothing to investigate further!Image...You have an engine in your car built by the Race Engine builder Jeff Hauser, it would be fitted with a High Volume Pump resulting in Higher pressure than a stock one, all these high performance engine builders Like Hauser, John Sleath, Dave Gilliver etc put high volume oil pumps in their builds.. you want high pressure, it's great, you shouldn't be concerned about high pressure in a engine built by a Drag Racing Man.. I talked about all this with my Race Engine builder Friend "Dave Gilliver" today, you also said when you had it checked "It's Right Where it Should be!.. it's confirmedImage now drop the hood down, drop the roof down, push your foot down and enjoy that Hauser Built engine My Ole FruitImage
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Julian
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Re: Oil sender conundrum

Post by Julian »

That’s the reply Ive been hoping to get :)
Car gets a fair amount of use with not a single issue in my time with it (since2007).

Will drive on a soon as I get home. In the meantime hertz have given me a nice SS Camaro to hammer :)
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Re: Oil sender conundrum

Post by Julian »

It does have a HP oil pump.
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Re: Oil sender conundrum

Post by Grant »

Good Man JulianImage
For anyone reading this >> A Standard/Stock oil pump on a Mopar is 1.5" deep, and high volume one is 1.75" DeepImage
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Re: Oil sender conundrum

Post by Steve Payne »

You can drop the oil pressure by fitting a softer spring on the relief valve. There are also adjustable ones available if you want to find tune it.
The sender with the original part number is available here https://www.ebay.co.uk/itm/353721348571.
I have fitted the new version that Robeys sell and it seems to be not very accurate, not saying this one is any better but it does have the correct part number for what we are supposed to use.

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Re: Oil sender conundrum

Post by Chris_R »

Steve Payne wrote: Sat Jul 15, 2023 12:51 pm You can drop the oil pressure by fitting a softer spring on the relief valve. There are also adjustable ones available if you want to find tune it.
The sender with the original part number is available here https://www.ebay.co.uk/itm/353721348571.
I have fitted the new version that Robeys sell and it seems to be not very accurate, not saying this one is any better but it does have the correct part number for what we are supposed to use.

Steve
Have you tried the one from Appleyards? He had a batch made by the original manufacturer and matched to an Interceptor Jaeger gauge. Made to original specifications but with modern innards. I don't know if Robeys are supplying the same one.
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shaun
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Re: Oil sender conundrum

Post by shaun »

The one I got from Andy recently sadly was not a faithful copy of the original.

Enough said.
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Julian
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Re: Oil sender conundrum

Post by Julian »

Thanks guys. Really appreciate the feedback and advice.

The sender (2 of) I got from Robeys pretty much matched the "mechanical" gauge so that suggests they are ok.

With regard to what I thought was possibly to-high-a pressure, Grant assures me it is ok. It is a Hauser built motor and the invoice notes a HP pump.

The engines run perfectly for me since 2007 so back on the road for me !
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