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View Full Version : Oil Pressure Issue LT-1-Please help.


caliguyinTN
10-08-2006, 08:23 PM
Today at the lake the oil pressure seemed quite low at 3400 rpms, alot lower than normal. Earlier in the day something plugged the water intake and engine got pretty hot until I put it in neutral and blew out whatever was clogging. Temp went back down to normal. But cruising back to the launch ramp the oil pressure seemed low. Then it dropped to about half on the dial and even alittle less than half still at 3400 rpms. This has never happened before. I only have 258 hours on it and I've been real careful about overheating. Is what happened today with the temp related to the loss of oil pressure? I checked the oil dipstick and everything was perfect. Idling into the ramp area i shut it off and turned it back on and oil pressure goes up then back down like normal. Any ideas? I'm thinking about taking it to the dealer here this week. I've only had the boat since beginning of august and this has never happened. Should I be worried?

caliguyinTN
10-09-2006, 11:50 AM
there's gotta be some engine guys in here, i'm looking for some help here.

BrianM
10-09-2006, 11:56 AM
Doesn't really sound like a problem to me. What is the pressure at half the dial? At 3400 rpm as long as you are somewhere in the range of 40 -60 you should be just fine.

caliguyinTN
10-09-2006, 12:05 PM
it just seemed like an issue because its never done that before. Especially the fact that the reading was jumping from normal to really low at 3400 rpms.

bigmac
10-09-2006, 12:07 PM
I'd be worried about that too. First thing I'd do is change the oil and oil filter.

While the engine oil is draining, I'd be pulling the raw water intake hose off the transmission cooler to look for a weed ball in the strainer. It's worth noting that rather than "blowing out" the clog, it was more likely "sucked in"

MYMC
10-09-2006, 12:33 PM
10lbs per 1000 RPM is what you should be looking for...a little more or little less is fine. If the engine got hot you will see a drop in oil pressure because the oil absorbs that heat as well and since there is no engine oil cooler it holds it longer.

True loss of oil pressure will take out a rod bearing immediately...there will be no time to react to the loss in pressure...rods bearings lead a tough life!

If the engine got hot change the oil and look for water...head gaskets in LT-1's donít like getting hot.

the legend
10-09-2006, 12:44 PM
i would agree10lbs per 1000 RPM is what you should be looking for...a little more or little less is fine. If the engine got hot you will see a drop in oil pressure because the oil absorbs that heat as well and since there is no engine oil cooler it holds it longer.

True loss of oil pressure will take out a rod bearing immediately...there will be no time to react to the loss in pressure...rods bearings lead a tough life!

If the engine got hot change the oil and look for water...head gaskets in LT-1's donít like getting hot.

caliguyinTN
10-09-2006, 01:37 PM
geez, if i took out a rod bearing, I would know immediately, correct? The oil pressure shoots up when I start it. I'm thinking the previous owner hadn't changed the oil too recent as to when I purchased it. I've put about 50 hours since I bought it, so if the oil has not been changed for a while previous to my 50, would this cause the oil pressure to drop the way that it did yesterday?

MYMC
10-09-2006, 03:01 PM
geez, if i took out a rod bearing, I would know immediately, correct? The oil pressure shoots up when I start it. I'm thinking the previous owner hadn't changed the oil too recent as to when I purchased it. I've put about 50 hours since I bought it, so if the oil has not been changed for a while previous to my 50, would this cause the oil pressure to drop the way that it did yesterday?
If you lost a rod bearing you would know right away...you'll hear it knocking. Hard to say if old(er) oil would have any effect like this...change the oil and see what you find. You can also send an oil sample out and see what they have to say about the engine condition.

caliguyinTN
10-09-2006, 04:32 PM
You can also send an oil sample out and see what they have to say about the engine condition.


Who and where would I send a sample to? I was thinking of taking it the MC dealership nearby and see if they could just run through the engine and see what they think the condition is and what may need attention. I bought it in August and I might want to know what could become an issue and then use the winter to address whatever comes up. Is that a waste of money?

MYMC
10-09-2006, 05:22 PM
Test kit: http: //www.dysonanalysis.com/premiumkits.html
Learn about oil: http: //www.bobistheoilguy.com/

If you are looking for a leak down or compression test then the dealer visit is a good idea.

Archimedes
10-09-2006, 05:33 PM
geez, if i took out a rod bearing, I would know immediately, correct? The oil pressure shoots up when I start it. I'm thinking the previous owner hadn't changed the oil too recent as to when I purchased it. I've put about 50 hours since I bought it, so if the oil has not been changed for a while previous to my 50, would this cause the oil pressure to drop the way that it did yesterday?

Change that oil man. First thing I'd do if I bought a used boat.

caliguyinTN
10-09-2006, 05:43 PM
yeah, you're right. The previous owner said i was good to go for the rest of the summer. I guess thats what I get for trusting his opinion.

Datdude
10-09-2006, 07:51 PM
my 1995 PS 190 LT-1 is weird when it comes to oil pressure. At idle or slow speed it is in the middle (40?), once the boat is on plane the oil pressure is pegged at 80. I check the oil every time I use the boat and everything seems normal. I have been told it is better to have high pressure over low pressure. I am thinking that my guage might be bad?

bigmac
10-09-2006, 07:55 PM
my 1995 PS 190 LT-1 is weird when it comes to oil pressure. At idle or slow speed it is in the middle (40?), once the boat is on plane the oil pressure is pegged at 80. I check the oil every time I use the boat and everything seems normal. I have been told it is better to have high pressure over low pressure. I am thinking that my guage might be bad?Mine has the same readings. Interestingly, the PZ-3 oil filter the boat came with had much lower readings, the Mercruiser filter the dealer put on at the 20 hour oil change was somewhat higher, and the Wix 51069 that's on there now reads the same 40-80 range that yours does.

caliguyinTN
10-09-2006, 07:58 PM
my 1995 PS 190 LT-1 is weird when it comes to oil pressure. At idle or slow speed it is in the middle (40?), once the boat is on plane the oil pressure is pegged at 80. I check the oil every time I use the boat and everything seems normal. I have been told it is better to have high pressure over low pressure. I am thinking that my guage might be bad?


My LT-1 was doing the same thing as yours until yesterday, thats why I'm alarmed. At idle or slow, at 40 (middle) and at plane and higher RPMS, pegged at 80. As of yesterday, not pegging at 80 on plane and even going below 40 at plane. I can hear the cash register going cha-ching when I figure out whats wrong or the dealer lays it on me. :(

Hrkdrivr
10-09-2006, 10:58 PM
Change the oil and the filter...when oil gets hot due to the overtemp it loses viscosity (thus the lower pressure) and it may not recover if it breaks down...good on you for even noticing the drop in pressure.

bigmac
10-09-2006, 11:18 PM
Change the oil and the filter...when oil gets hot due to the overtemp it loses viscosity (thus the lower pressure) and it may not recover if it breaks down...good on you for even noticing the drop in pressure.
It's not the oil that breaks down from heat (or shear), it's the viscosity index improver, which is what makes a multi-viscosity oil. Group II base-stock oils like all API CH-4 or higher don't use much VI improver, so loss of viscosity is generally negligible these days in overheat or high-shear conditions.

I agree that the oil and filter should be changed, but I was thinking more along the lines of fuel or water dilution.

Hrkdrivr
10-09-2006, 11:44 PM
I defer to the man w/better knowledge! I saw this a couple times in older cars when a radiator hose blew, the engine overheated and then the oil pressure dumped. After fixing the cooling system, the oil had to be changed because the pressure wouldn't stay in limits. Regardless, oil is cheap and engines are expensive!

caliguyinTN
10-10-2006, 12:00 AM
Okay, the consensus seems to be to start with changing the oil and oil filter. Since I have yet to do this on my first MC, what oil is the BEST and what filter is the BEST for the LT-1?

bigmac
10-10-2006, 08:45 AM
Okay, the consensus seems to be to start with changing the oil and oil filter. Since I have yet to do this on my first MC, what oil is the BEST and what filter is the BEST for the LT-1?Any nationally branded oil that meets or exceeds the API service classification called for by the engine manufacturer will be fine. Pennzoil Marine (http://www.pennzoil.com/products/marine/4cycleHDoil.html) or Rotella T (http://www.shell-lubricants.com/products/pdf/RotellaTMG.pdf) in 15w40 seem to be most readily available. (Note that Pennzoil® Long-Life™ Heavy Duty (http://www.pennzoil.com/products/LongLife/pickups.html) Engine Oil is the same as Pennzoil Marine). If you're into synthetic and don't mind spending the money, Amsoil Heavy-Duty Diesel & Marine (https://www.amsoil.com/storefront/ame.aspx) is also good. There's also Mobil Delvac 1300 Super (http://www.mobil.com/USA-English/Lubes/PDS/NAUSE2CVLMOMobil_Delvac_1300_Super.asp). Any oil that meets CH-4/SJ or better will be just fine. Current API service classification for those oils is CI-4/SL (now, or soon to be CJ-4). PC-10 oils are a new sub-category of diesel application that appear to be more suitable for engines with anti-oxidation exhaust devices. I'm not sure if catalytic converters such as are now on current Indmar engines fall into that after-treatment category, but I don't think so. Anyway, I wouldn't spend any effort looking for a PC-10 oil for my boat - I'm not sure it's the right application, and those oils, if there are any yet, may only be available from jobbers anyway, so far.

Filters - there is much wider variability is filter quality than there is in oil. It's not just filtration, but also construction, especially drain-back valving. Here (http://minimopar.knizefamily.net/oilfilterstudy.html)is a kind of general overview testing. Fram (made by Allied Signal) is one of the more ubiquitous filters out there, but is not very highly rated. Look at this email (http://minimopar.knizefamily.net/oilfilter-fram1.txt)that that oil filter study guy got from an Allied Signal engineer...

Note that the Pennzoil oil filters are made by Fram. My boat has "Pennzoil recommended" stickers all over it (along with "Sta-Bil recommended" stickers), so I assume Indmar has some kind of marketing deal with Pennzoil/Quaker State.

caliguyinTN
10-10-2006, 11:31 AM
Will either of these oil filters fit my 96 LT-1?
NAPA Gold filter part number is FIL 1069 or Wix 51069.
Also whats a good brand of oil?

MYMC
10-10-2006, 12:52 PM
More information than you'll ever need on marine oils is found here: http://theoildrop.server101.com/forums/postlist.php?Cat=0&Board=UBB13

Filter information: http://theoildrop.server101.com/forums/postlist.php?Cat=0&Board=UBB6

BrianM
10-10-2006, 01:03 PM
Will either of these oil filters fit my 96 LT-1?
NAPA Gold filter part number is FIL 1069 or Wix 51069.
Also whats a good brand of oil?
Either of those filters is a great choice and will fit. I run the NAPA Gold 1069 in my boat.

Sodar
10-10-2006, 01:04 PM
Will either of these oil filters fit my 96 LT-1?
NAPA Gold filter part number is FIL 1069 or Wix 51069.
Also whats a good brand of oil?

I have asked this question a few times, but have never gotten a definitive answer as to a part number for the oil filter. I was told that any Chevy 5.7 L oil filter would work, but that seems a little vague for me. I was also told by Indmar that and I quote: "Everything is the same [as the 5.7 MPI] except for the serpentine belt and fuel filter. The Indmar part number for the belt is S725010 and the fuel filter is S556003."

I hope this helps a little. It is hard when you buy a used boat and have no true documentation such as owners manuals!

Archimedes
10-10-2006, 01:26 PM
(Note that Pennzoil® Long-Life™ Heavy Duty (http://www.pennzoil.com/products/LongLife/pickups.html) Engine Oil is the same as Pennzoil Marine).

Big Mac, are you 100% sure of that? Reason I ask is that I bought 3 quarts of the long-life when I couldn't find the Marine, but then later found the Marine oil. Was wondering if I could mix em.

The long life I'm talking about is the one that says Diesel on the label.

MYMC
10-10-2006, 01:38 PM
I don't think they are the same anymore as the LL no longer has MO.

bigmac
10-12-2006, 12:44 PM
Big Mac, are you 100% sure of that? Reason I ask is that I bought 3 quarts of the long-life when I couldn't find the Marine, but then later found the Marine oil. Was wondering if I could mix em.

The long life I'm talking about is the one that says Diesel on the label.I'm about 99% sure they're the same oil, but I'm 100% sure you can mix them. Assuming the Long Life diesel you're talking about is listed with an API service classification of CH-4/SJ or higher. If it's not, you can still mix it just fine, but the oil technically won't be up to Indmar's requirements.

caliguyinTN
10-12-2006, 01:04 PM
The local MC dealership checked out the engine and the oil pressure issue. Said everything was great, a loose wire for the sending unit to the guage. Had the oil changed and filter. Had them put in a NAPA Gold 1069 and some Mobil Delvac 1300 Super oil (per Diesel's advice, thanks). Also winterized it, changed the impeller and serviced the tranny. I should be good to go until the spring. It was about 30 degrees last night which means my boat crew has put their skis up for the winter. So come next spring, hopefully all the oil issues will be a non issue. Thanks for all your advice and thoughts everyone.