Quote:
Originally Posted by tomtom72
I thought that the 405 hp motors got exh & Int valve stem oil seals? I'm almost positive the 375 hp motors are missing one or both, I think it's only the exh seal they left out?
Anyway, GOFAST how are your PCV valves? I change mine every year as part of my "get ready" for the season. I have noticed that they don't make that clear metallic clinking sound after a season's worth of use, for me somewhere between 6k to 8k miles. As I get towards season's end my oil use goes up or becomes accelerated if you'll allow me that phrase. I can't find the oil on the plugs. Anyway, my point is my LT5's use seems directly related to the health of the PCV valves...or at least that's JMHO thru my own observation. Oh yea, pounding on Her just seems to speed up oil loss no matter when I do it. One of the development issues LOTUS had, ccv blow by ( my words, not LOTUS ), as there is no place for the internal wind with oil in it to slow down enough for the oil to coalesce and fall out of the air stream. Or at least that's what I think they, LOTUS, was saying. I would think that if that is true, then how clean the PCV valves remain over their time in service would be very important to oil loss?
As for checking the oil level. I use my car only on weekends and that's when I check my oil as part of my pre-start up check list. I always get consistent readings from the dipstick. If you think about all the places in our heads that oil can hide I can easily see 4 or 5 hrs should pass before all the oil gets back to the pan. Okay maybe a bit less?
These are just my observations with how my engine behaves in this regard.
Tom |
Hi Tom,
Your're correct, far as the 90s go. They were sans seals on the exhaust valves - per Lotus Engineering felt those valves needed extra lubrication (ref: Heart of the Beast?). I've also read where the particluar open deck architecture employed in the LT5 is prone to some oil consuption, as a result of the top of the sleeves anchored to the head via friction. Sleeve lenght uniformity is absolutely critical to oil consumption, and tollerances being tollerances, and vibrations and stress being what it is (read: sleeve instability), sleeve stability contributes to oil consumption.
Marc's caging the sleeves in his BIG inch builds seems to be addressing at least some of the oil consumption (have to ask 'im or Frank U) by stabilizing the sleeves (reducing the dependance on friction against the head for stability). I've not heard yet if AES' closed deck design is effective in reducing oil consumption, but clearly that design stabilizes the sleeves as well.
(
Maybe someone with REAL expertise could chime in? 
)
Comments about "first quart" consumption was news to me. And too can you or anyone tell me if the hashed segment on the dip stick represents a quart or is it something less? I put in a quart when the level was just below the hash, and checked it the next day. The level now as above the hash (full) line by an equal amount....WTF? I'm wondering if the seal on the dipstick caught on the edge of the tube and maybe didn't allow a proper sounding of the oil level. Have you (or anyone else) ever noticed that??
From the way I drive (spirited ... Hey, living in the country has its advantages!
), my consuption has always been a quart and a little more between 5000 mile changes. After getting hot a couple times, and having a coolant disaster once, I'm monitoring it closely for a while to see zackly what it is now. (I have seals on all valves now).
Gotta run!
P.