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Oil pressure issues on tbi350

Old January 22nd, 2019, 3:58 AM
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Default Oil pressure issues on tbi350

Hi, I swapped in an 89 TBI 350 engine into my jeep and it ran fine but had blow by and excessive oil consumption so I decided on a rebuild. Disassembled the motor and sent it off to the machine shop to have them magnaflux, hot tank, bore and hone, hang pistons, grind crank, balance, and install cam bearings, frost plugs and oil galley plugs. The heads where swapped at a local cylinder head shop that does excellent work. I did the rest of the assembly with quality parts and didn't run into any problems even measuring bearing clearances with plastigauge were well within spec (.002). Installed the motor back in my jeep and it fired up no problem but I noticed there was very low oil pressure when I started it so I shut it off. Put an oil pressure test gauge and still got the same result of around 10psi. Is there anything I could've missed during reassembly? During assembly I installed a new melling m155 oil pump with the 3/4" inlet vs the original 5/8" inlet pump and set pan to pickup clearance to 3/8", could the pump be a problem? Is there some hidden oil galley plug that may not of been installed by the machine shop, there's no oil leaks?
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Old January 23rd, 2019, 8:00 PM
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Originally Posted by c5wagner View Post
Hi, I swapped in an 89 TBI 350 engine into my jeep and it ran fine but had blow by and excessive oil consumption so I decided on a rebuild. Disassembled the motor and sent it off to the machine shop to have them magnaflux, hot tank, bore and hone, hang pistons, grind crank, balance, and install cam bearings, frost plugs and oil galley plugs. The heads where swapped at a local cylinder head shop that does excellent work. I did the rest of the assembly with quality parts and didn't run into any problems even measuring bearing clearances with plastigauge were well within spec (.002). Installed the motor back in my jeep and it fired up no problem but I noticed there was very low oil pressure when I started it so I shut it off. Put an oil pressure test gauge and still got the same result of around 10psi. Is there anything I could've missed during reassembly? During assembly I installed a new melling m155 oil pump with the 3/4" inlet vs the original 5/8" inlet pump and set pan to pickup clearance to 3/8", could the pump be a problem? Is there some hidden oil galley plug that may not of been installed by the machine shop, there's no oil leaks?
Is your 350 connected to the stock Jeep oil pressure Guage?
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Old January 24th, 2019, 5:36 PM
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Originally Posted by oilcanhenry View Post
Is your 350 connected to the stock Jeep oil pressure Guage?
Yes, but I confirmed the gauge reading with an oil pressure tester kit and it seems 15-20 psi cold at 2200 rpms and nothing at idle. I've come to suspect this galley plug (grey arrow) was never installed by the machine shop and I sure didn't put one in so I'm going to confirm today.

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Old January 24th, 2019, 6:18 PM
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So confirmed that plug was never installed under the main bearing cap and found out neither where these 3 under the timing cover once I pulled the oil pan and timing cover, the cam is a little too worn as well as the bearings so the engine is coming out for some new parts again. Last time I don't double check something a machine shop was supposed to do.
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Old January 24th, 2019, 8:01 PM
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Nice catch but frustrating; send them a bill
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Old January 27th, 2019, 12:59 PM
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So they are actually replacing all the rebuild parts and doing the labor for me since the work order clearly shows that they were supposed to install all expansion plugs!
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Old January 27th, 2019, 4:57 PM
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Good for them to recognize their error - and great for you!
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