Stumped! Engine stall after start

[alldodge]

Oil pressure switch should be 805024 or 87-864252A01 (old and new numbers)
Oil pressure sensor should be 815425T or 8M0068784

Your electrical parts can be found here
https://www.mercruiserparts.com/bam/subassembly/31511/2694/60

Your motor is here
https://www.mercruiserparts.com/4-3lh-gen--4-bbl-gm-262-v-6-1998-1

Here is your electrical diagram

 

[Scott06]

As stated CK with a mechanical gauge you. An get one for $20 at an auto parts store. Not a bad tool to have. With a new engine you can get a baseline but given the numbers you have I think your gauge is not accurate

 

[MadMick]

I swapped out the oil pressure sender and oil pressure still at 70psi at idle and goes to 80psi when RPMs are increased. I didn’t pressure test as suggested by a few of you because honestly I am very gun-shy at this point and don’t trust myself to get that right. So I dropped off boat to local marine mechanic this morning to do his thing on the boat. This way I can be confident that an expert has looked it over, fixed or can give me the green light and I’m not going to be overly nervous when I put her back in the water.

I aporeciate everyones help with my issues and will post a final result if/when mechanic looks it over.

What I have learned on this journey:
1. Do NOT use Teflon tape on sensors and confirm if it’s a single or dual stage sensor you need and you get.
2. New out of the box OEM parts do fail
3. Buy a box of bandaids as your hands and arms ARE going to get cut up with sharp zip-ties and pipe clamps!!
4. Even when you do everything by the book things can & will go wrong.
5. When issues occur check your GROUNDS!! lol
6. Even the smallest and most simple issue can make an engine not run or not run good.
7. Do not be afraid to ask for help and advice when you get in a jamb.

Best,

MM

 

[greno]

Sounds like a good course of action. Let us know what the mechanic finds. I would be surprised if they put a high-pressure oil pump in a crate engine. Unless it was destined for the drag strip.

 

[MadMick]

Greno, I honestly wouldn't know the difference between a HP oil pump and a regular pump....lol. The last 5/6 weeks has been an absolute blast working on this engine. For someone who knew nothing about how an engine operates I have learned an awful lot BUT I am still a novice and to be honest I hope I never have to do this again!! When I told this to my boatie friends they all laughed and said the only way that I will never go through this again is to get out of boating....lol

Best, MM

 

[MadMick]

I am back in business!!

AllDodge - there is in fact a HP oil pump installed in my motor.

So the mechanic tested everything out and I got the all clear to put her in which I did within hours. Been 6 weeks off the water so I was busting to get back out.

Boat ran like a clock, engine temp, oil pressure and everything else was as I was told to expect. Landed fish, watched the sun go down and the moon rise on the water!! I am stoked!!!!

Just doing my break in of the motor per directions....

A huge thank you to all who weighed in with help, advice and guidence.

Best to all,

MadMick

 

[greno]

Glad you got it sorted out. That HP oil pump won't hurt anything other than some additional parasitic loss. Takes a bit more power to run an HP oil pump. Great you got back on the water. Any day you can land fish is a great day!

 

[alldodge]

My opinion:
Things that go with high volume oil pump in a motor that doesn't require one.
More HP needed to turn the pump
More strain on distributor gear
More heat generated in the oil (will need a larger oil cooler)
Oil lines for remote are to small for volume
Remote filter adapter is not sized for volume (again to small)
At high RPM's there is a risk of running the pan out of oil (4.5 qt)

 

[greno]

He has a High-Pressure (HP) oil pump not High-Volume (HV).
Most of these just set the bypass spring a little higher. If its a Melling and he wants to change it he can to a lighter spring.
I've not seen anyone running the pan out of oil with an HP pump at any RPM that a marine engine operates at. 7 to 8,000 RPM race motor, yeah, possibly. 4500 RPM, not happening.

 

[alldodge]

Again, says one man's opinion

Wonder how you get high pressure with out applying more volume then the leaks can dissipate?

 

[greno]

Here you go.

 

[alldodge]

You might be an expert but so far you have posted nothing which indicates this is the case.
Standard 55 - 60 psi
HP 75 - 80 psi
HVHP 70 psi

The only thing you have posted which backs up a claim is the 80 psi, and not running the pan dry, but that's it. A motor is a controlled leak, so bearing surfaces have given clearance. Increasing pressure increases heat, load and other issues as previously stated.

If the OP has a HP pump and hope not a HVHP pump that part is good, so leaking, but the pressure and load will still be higher then normal. Find info which backs up your opinion and/or knowledge and I'll yield. Just spouting off info out of context of real world is not provinding any additional info to anyone.

I'm old and look forward to learning something new. My Melling HVHP pump in my Formula will produce over 80 psi when cold, and my motor was built with added clearance to use the pump.

 

[greno]

Good you viewed the video. Now you know the difference. Which you didn't know before or you wouldn't have posted the question.

 

[alldodge]

Your funny, missing what the OP posted and what is actually going on.

 

[MadMick]

Gents the input is all great. Here is what I am told is installed on the engine.

Says HP & HV oil pump. If in fact I need to upgrade other parts on my engine to avoid any issues with it then please let me know and I WILL update those as needed. I don’t want to screw this up by not doing so.

While I love the all the help the banter back and forth is just confusing me.

So again based on what you know about my engine please suggest any/all upgrades I may need.

Best,

MM

 

[alldodge]

My concern comes from seeing 70 psi pressure with the motor all warmed up at idle. If you gauge showed 40 psi or so I would not be as concerned.

I'm running a HVHP pump and cold idle its 65 psi, warmed up idle around 40, cruising at 3800 to 5200 rpm its 70. If I take off before warm up I'll see 80+. My motor was built with increased tolerances (530HP), but did not have the right size cooler. The motor was running fine, motor temp no matter what speed was good.

Wondered why my oil was getting black so fast, and after some discussion installed a oil temp gauge. Oil temp would exceed 260 degrees (would not let it go higher) at WOT and normal cruise 240. Could go further in depth of finding and resolving my issues but this is about your motor.

Now there may just be a gauge issue, don't know. You don't have much oil to work with, but maybe a easy thing to do is use a IR temp gun and measure what the oil filter temps are at warm up, while cruising, and after a long cruise.

Does your oil pressure stay at 70 all the time no matter what?

 

[MadMick]

All Dodge,

At startup (cold) the OP reads between 70 and 80psi. I haven't taken motor above 3,000rps as I'm still in the break-in period and to be honest I usually don't run above 3,000 rpms anyway. 3,000 rpms give me 18 to 20 mph. During a run the OP stays pretty much the same until I idle her down and the OP then drops to between 50 and 70psi but will increase back up to 70/80 psi if i increase the rpm's again. The engine temp once warmed up reads a steady 160 to 170. I will check the temp of the oil filter with my IR temp gage tonight when I take her for her daily run and report back. Again if I need to upgrade anything to protect my engine with a HP/HV oil pump then I will do so. I just want it right.

Best,

MM