rgaynor85

ok im lookin into buying a 98-02 t/a but ive been reading and doin searches and i see everyone mentions the 98-99 ls1's have a issue with some holes inside the block causeing oil starvation to one side, also some say its the oil pump, can someone give me a correct awnser to what the actuall issue is and if a oil pump upgrade will solve the problems, i plan on bolt on and a supercharger in the future just so u know.please lemme know thanks

M_T_0

the issue with the early ls1 oil pumps is the releif valve/valve spring.
the deal with the ls1 is that the cam gallery gets the oil first and the crank gets its oil last, so the ls1 requires a lot of oil pressure in order to keep it happy (this is not a bug it is a feature lol).

the early oil pumps would have the releif stick in the open position thus allowing the oil pressure to drop into the 20's at idle and low rpm's, this is not good due to the non-priority main oiling system.

the later oil pumps 2001 and later i think, had an improved spring/valve setup. if you are planning to buy a car equiped with an LS1 just check the oil pressure at idle, it should be > 30psi. also if you plan to add a blower you will be pinning the crank and it would be in your best intrest to replace the oil pump at that time with a later than 2001 oil pump (a ported and shimed pump would be even better).

also porting and shimming an oil pump takes about 2 hours to do and is not that hard to do once the oil pump is out of the car.

More Than Zero

ps while replacing the oil pump I would do the cam and replace the timming chain with an LS2 chain.

rgaynor85

does that mean less than 30psi or more or just are u pointing to what u wrote lol sorry im stupid sometimes

66deuce

iTrader: (1)

no,it doesn't have to be 30 psi at idle.i have just over 20 psi at a hot idle and have never had any problems,2 yrs. on a ported oil pump.i can't remember off the top of my head,the specs that GM gives is a lot less than 30 psi at a hot idle.

nickls1

iTrader: (2)

I just had mine checked mechanically. The specs call for at least 6 psi at idle when hot. I thought this was ******* insane, but thats what gm calls for. I think mine was 20 so I know I am ok.

rgaynor85

so does anyone else have an opinion on this, is what he said above true about the oil problem just being the pump hanging up...

moeZ28

iTrader: (7)

i have a ported ls6 oil pump and my oil pressure never drops below 40psi, even at hot idle. but my cars temp never gets above 185 thanks to a 180degree thermostat and some hp tuner magic.

rgaynor85

40 is not to high for idle

66deuce

iTrader: (1)

seems like i read on the board here awhile back about some 98 models where the pump would just let go without warning.i don't know the exact cause.when i did my H/C swap i put in a ported one for insurance.

66deuce

iTrader: (1)

yeah,i was thinking around 7 psi was what my book says,that does seem awful low.but with tighter tolerances and thinner oils,you don't need as much pressure.and having too much can actually can rob horsepower.

LS1-450

iTrader: (33)

Many of us idle in the 20's w/ no problems. As long as pressure builds with RPM, it should be ok. Keep searching threads & you'll find one where a guy who has built many new engines w/pumps noted that more often then not, they idle in the 20's. If you are worried, install a new pump. For sure, keep an eye on the oil pressure.

M_T_0

yes it is true that some cars run with hot idle in the 20's or less, and the book says that 6 or 7 is ok at idle. now with that said if you have a car that has that low of an oil pressure great, but the question is about buying a used car and I would still look for one that has > (> == greater than) 30 at idle, why? because I know that one that has > (greater than) 30 at idle is not going to have a problem. will a car that has less than 30 at idle have a problem? probably not but it is your money.

and yes the oil pump springs/valve in the 98's were the most prone to go out.

I run at 40+ at hot idle after installing a shimed and ported oil pump in my 99 C5, it was at 30+ before the replacment pump.

JMO

More Than Zero

SSCamaro99_3

iTrader: (1)

Katech oil pump with cam swap. 60 psi cold idle, 42 psi warm idle.

69GMC/99LS1

Not to hijack, but how much shim do you add when shimming? Any of you veterans have a handy little formula like .010" shim = +10psig or something like that???

M_T_0

.080 will get you around 10psi at low rpm and on the top end 15psi or so. I used small SS washers, it took 3 to get the .080 also be sure to use locktight on the cap (you do not want that thing backing off wile you are going down the road), also put the washers on the end of the spring that is in the cap not the valve.

More Than Zero

DrkPhx

iTrader: (15)

Contrary what alot a people say about a supposed widespread bad oil pump problem for the early LS1's I still have yet to see any documented failures. My 98 had 20 psi at hot idle and 45 psi at hwy speeds since day 1 with zero problems. The holes in the block you refer to are a different story. I think they are the real culprit because for 97-98 blocks GM had to drill the holes to help minimize oil starvation at high rpm/loads. Then they changed to having the holes cast into the block for later models. A side by side comparison of the two reveal a big difference in the size of the holes. Hope this helps.

rgaynor85

so the newer blocks holes were bigger

'Trust'

iTrader: (24)

Yea, if i remember right, the pump wasnt the problem for starvation, it was the smaller holes as talked about, that at higher rpms didnt get enough oil to their designated areas, (upwards of ~6300 rpms) so it was fixed for the later models. The pumps give out because of that small spring

DrkPhx

iTrader: (15)

Yes, that is correct. A picture would be worth a thousand words to show you.

rgaynor85

so if your not pushing you motor past its limits and keeping it at or below redline you should have no problems with those small restrictive holes??