Transverse V6 & Oil deposits

Messages
392
Location
Toronto, Canada
Today, I replaced my valve cover gaskets on my 89 Acura Legend with close to 200,000 miles on it. The engine is smooth as an electric motor and does not consume oil anymore. It is now in the second rinse phase of AutoRX. The first clean cycle was followed by a quick rinse of 1,000 kms and then another long rinse of 4500 kms. The second AutoRX treatment was also 4500 kms. ( I made a trip to the west coast and back) When I removed my valve cover gaskets I could not believe my eyes! The engine was still filthy. The valve covers needed major cleaning with solvents and a small stainless steel brush. I thought AutoRX was supposed to "break" this down. Furthermore since 12 years ago, this auto has had the 5,000km or 3 months routine pretty much all the time. I never expected this. Don't get me wrong, Auto-RX has smooth out the engine and it is now much quieter ( my lifters never ticked before either). What I noticed was that the front portion of the V6 had a lot of "grit" and carbon and was a dark red brown. The rear bank however had a golden patina and was much cleaner. Why was there a drastic difference in the way deposits and sludge builds up on this engine??? or a tranverse V6. All I can think of is the difference in cooling between the banks.
 

cangreylegend

Thread starter
Messages
392
Location
Toronto, Canada
Car has generally had dinos 5w-30, mostly Castol GTX and Pennzoil. Had a couple years of Group III though. Filters, OEM, Fram and Purolator. The odd thing is that the rear bank was generally OK but the front bank had a lot of grit where the deposits turned to Carbon. No cooling problems, climbed the Rockies and the gauge barely budged any. Every couple years it's had a complete reverse flush. The only issue is that the front O2 sensor is still original. Can a richer burning bank cause deposits ONLY on one side???? Just had an O2 sensor code for the REAR though. Reset ECU and it never came back, but a sensor for the rear is on its way. The PCV valve is off the front bank though.
 
Messages
4,478
Location
Southern California
I'm probably way off base here, but since your Honda V6 (ok, Ok, OK, "Acura"!) is proabably like many other V6s in that there's a metal shield over the "front" exhaust manifold, lest the mentally challenged among us fry the ten nubs off his little hanny-pads, maybe the trapped heat in that head results in more tendency for oil to cook on that head. Anyway, just a thought... [I dont know]
 

KW

Messages
1,686
Location
Central Arkansas
The front valve cover will run cooler and not be able to evaporate any water condensation as well as the hotter rear cover. Did you do a lot of shortish trips with it?
 
Messages
622
Location
42.4N 85.7W
Strange, never had that problem in our V6, or any of our many V4s. OH, TRANSVERSE! Our normal *COUGH*Subaru*COUGH* cars cool evenly between banks. [Razz] Sorry, just had to get that in there, Honda does make some fine equipment. Seriously though, there are so many factors that COULD be the culprit, or it could be a combination. It's even possible that, knowing that the front may run cooler, the engineers designed the front to run warmer, but over-compensated a bit. Dave
 

cangreylegend

Thread starter
Messages
392
Location
Toronto, Canada
My thoughts are that the front bank would run cooler than the rear. If so, there should be less carbon but there is more. And yes, it did quite a few of shortish trips but the oil was changed every 3 months regardless to compensate for that.
 
Messages
656
Location
Massachusetts
PCV valve is in the front. Hmmm.... Is there a vent to the intake system on the rear valve cover? If so, there maybe an answer here. If the PCV gets clogged and the car runs a period of time with it closed at all times, the entire engine is filled with unburnt fuel fumes, EGR gases and such. The rear head (assuming there is a vent) vents these gasses off to the intake to be reburnt in the reverse of its intended function. That vent is there actually so that engine vacuum through the PVC does not compromise the seals. Ok - now picture this scenerio for 20 - 30K miles. All that carbon from the exhaust, unburnt fuel fumes, some water vapor, some volitalized dino oil all swrilling around the crankcase and heads, with only a little tiny vent to the intake, before the throttle body, to go to. Mind you, these gases should be going through the PCV valve under manifold vaccum AFTER the throttle body. So asssuming even cooling of each head, it would make sense that the vented one would have less garbage stuck inside, than one that is realitively sealed by the stuck PCV. How's my theory so far? To prove it, I would imagine that the intake tube and throttle body has some carbon deposits and black sludge. This of course is just a theory coming from a guy whos never even seen the engine compartment of an Acura. [ June 16, 2004, 10:40 AM: Message edited by: crashz ]
 
Messages
4,874
Location
MN
quote:
Originally posted by seotaji:
quote:
or any of our many V4s.
wow, when did they make a v4?

Honda has made several V4s. The Magna and RC51 both have them. Don't think they used them in any cars though. [Wink] -T
 
Messages
9,427
Location
Pensacola & Vero Beach FL
quote:
Originally posted by seotaji: lets stick with cars people, cars!! [Wink]
Why??? I don't recall this forum being BobIsTheCarOilGuy.com! [Wink] I suppose you could debate about which rolls off of the tongue easier, BITOG or BITCOG, though. Hmmm, come to think of it, BITCOG does have a nice subliminal mechanical suggestiveness to it that will probably appeal to the psyches of those inclined to come here in the first place. Ooops, now we're way [Off Topic!] , sorry 'bout that. To bring this back to topic, if you find that the mechanicals are functioning properly, I'd consider switching to synthetic oil. Yes, dinos are fine for many applications, but it's equally apparent that in some engines, they just can't cut it. Obviously, there are many differences between your 89 Honda/Acura V-6 and my 88 Honda I-4, but my 88 Civic went for 10 years and over 150k miles on a diet of Mobil-1, and when I parted with it, the inside of the engine was absolutely spotless, not even a hint of a layer of varnish developing. I flogged this engine mercilessly in a hot climate, and never had any trouble with it. None of this proves anything with respect to your engine, but I think it's fair to conlcude that you may benefit from trying a synthetic (again, if your engine is otherwise working as it should). You might try a couple fills of an ester based syn (Neo, Red Line) to take advantage of the ester's better ability to get foreign substances off metal surfaces. Whatever you do, good luck with it. [Cheers!] Edited for typo.
 
Messages
4,874
Location
MN
quote:
Originally posted by DriveHard: Pretty sure the RC51 is a V-twin.
Your right, the RC45 was a V-4. The RC51 replaced it with a V2. -T
 

cangreylegend

Thread starter
Messages
392
Location
Toronto, Canada
I think crashz is onto something here. The PCV was replaced last year. However, the old one was not stuck and seemed to still operate. The PCV valve theory is plausible. However, the crankcase is share by both banks so the type of crankcase gas that is seem by the banks is the same. I suppose there is more flow thru the PCV than just the breather, right? If so that will explain it. It appears that AutoRX did free up some stuck rings as my engine is much smoother than before the treatment. However, the car never really consumed oil as it was mainly leaking thru the gaskets. ( fixed now)
 

cangreylegend

Thread starter
Messages
392
Location
Toronto, Canada
I think crashz is onto something here. The PCV was replaced last year. However, the old one was not stuck and seemed to still operate. The PCV valve theory is plausible. However, the crankcase is share by both banks so the type of crankcase gas that is seem by the banks is the same. I suppose there is more flow thru the PCV than just the breather, right? If so that will explain it. It appears that AutoRX did free up some stuck rings as my engine is much smoother than before the treatment. However, the car never really consumed oil as it was mainly leaking thru the gaskets. ( fixed now)
 
Messages
2,077
Location
Cordelia, CA
quote:
I suppose there is more flow thru the PCV than just the breather, right? If so that will explain it.
The purpose of the Positive Crancase Ventilation system is to remove blowby(unburned fuel, steam, CO2, plus all the usual nasties) and put it back into the intake stream, so yes, it's much more than just the breather.
 
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