1998 Eddie Bauer

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ChancesDad96

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Hello all, I am in need of some input. I purchased a 1998 Expedition 5.4 a couple months ago with 164,000 miles and found out it had no oil pressure once it warmed up good. I put a new melling oil pump in it and replaced the timing chains, guides and tensioners while I was there. Truck fired right up, pressure gauge shot up. Motor got to temperature, oil pressure dropped, came up, dropped came up about 3 times then went away completely. Shut the truck off restart it oil pressure gauge shoots up... So I replaced the oil pressure sending unit same thing...
As a side note I am also having a problem with the GEM. Not sure if it is connected,
Please help...
 

WILLIAM ESHELMAN

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Maybe oil pressure sensor or something in that circuit. It'd probably be good to buy a consumer All Data subscription for the vehicle.

That way -- less guessing.
 

TobyU

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Definitely get a gauge on it.
You more than likely did all the work when it had pressure all the time.
My wife's 2000 did that. At first we shut it right off and were afraid it had no pressure but later found out it was the sending unit. It would only do it when cold start but in like 20-45 seconds. After that it was fine.
If I tapped on the sending unit when the gauge dropped and red light of death came on it would show pressure and bounce.

If you really had no pressure a 5/4 would start clicking in less than a minute then shortly after start squealing like a slipping belt as right before the cams start welding themselves to the aluminum saddles in the heads.
Ask me how I know....
 
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Buy an Motorcraft Oil pressure sensor. it is right by the filter. its a pain to get to but worth it. I bought an aftermarket and it did it again after 3 days. Now, its all good. no more issues. As much as possible only buy Motorcraft for the Expys. Also< Harbor Freight has an inexpensive pressure gauge kit that shows the actual pressure.
 
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Hello all, I am in need of some input. I purchased a 1998 Expedition 5.4 a couple months ago with 164,000 miles and found out it had no oil pressure once it warmed up good. I put a new melling oil pump in it and replaced the timing chains, guides and tensioners while I was there. Truck fired right up, pressure gauge shot up. Motor got to temperature, oil pressure dropped, came up, dropped came up about 3 times then went away completely. Shut the truck off restart it oil pressure gauge shoots up... So I replaced the oil pressure sending unit same thing...
As a side note I am also having a problem with the GEM. Not sure if it is connected,
Please help...
 
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"I just GOOGLED your issue" It's not the oil pump; [it's your rod bearings coming loose] I highly recommend you not drive it til you replace the connection rod BEARing's! If you drive it from start-to- highway speeds; you'LL throw a rod doing so!!
 

TobyU

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"I just GOOGLED your issue" It's not the oil pump; [it's your rod bearings coming loose] I highly recommend you not drive it til you replace the connection rod BEARing's! If you drive it from start-to- highway speeds; you'LL throw a rod doing so!!
You're joking right??
 

Ulver

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"I just GOOGLED your issue" It's not the oil pump; [it's your rod bearings coming loose] I highly recommend you not drive it til you replace the connection rod BEARing's! If you drive it from start-to- highway speeds; you'LL throw a rod doing so!!
We know you're excited to throw in a diagnosis on this thread.. but.. Instead of telling him to throw parts at it, especially something that time consuming- let him know HOW he can properly identify
the issue before he wastes his time.

For example, posting something like this that could lead him to the right conclusion. https://itstillruns.com/check-bad-main-bearings-8198999.html
 
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