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Guys,
I took the unfinished car to our local lapping day on sunday, and when i was hitting upper RPM;s under hard acceleration, i was getting some smoke out of the exhaust. It was greyish color. I did a compression check, and I had 125-130 on all cylinders. The head gasket was replaced recently also.
Any help would be great.
Adam
Sounds like maybe some oil blow-by either getting past the rings or the valve seals. How many hours/miles on the top and bottom ends? are they stock or worked? Thats my 1st assumption...but obviously its hard to say w/ so little info...was it running hot at all?
-dw
with blow by though, wouldnt it leak down, or have low compression? engine has 187,000 on the odm, has not been rebuild to my knowlegde, or been overheated. im thinking valve seals, hopefully. But im worried if i get the head rebuild, it will make the rings start leaking.
What year is your car? 125-130 sounds a tad low.Quote:
Originally posted by abower1:
Guys,
I took the unfinished car to our local lapping day on sunday, and when i was hitting upper RPM;s under hard acceleration, i was getting some smoke out of the exhaust. It was greyish color. I did a compression check, and I had 125-130 on all cylinders. The head gasket was replaced recently also.
Any help would be great.
Adam
1989
Actually, it was 135, typo.
I found out last night the igtnition was retartded all the way, im oing to have to time the egine tonight. i know it was running very rich, so ill see how much that helps. if all else fails, i guess i can get the head rebuilt.
If you brought me a 10 year old honda w/ 185k miles on it and it checked out at 135psi I'd say it had decent compression....if you brought me and IT race car w/ 135psi I'd say it was time for a full rebuild. most race motors are rebuilt by the hours, so racing with a motor that is just shy of 200k miles boggles my mind...and you wonder why it might be smoking at upper rpms?? That said...an over rich condition can/will also wash down the cylinder walls and lead to blow-by past the rings. If you believe all else is well in the motor, that could be the culprit...but given the high mileage and the timing being off...well...maybe its time to freshen it up a bit?? if for no other reason so you have a bit more confidence in it while on the track...
-davew
-dw
I fought a smoking problem this past season (as those racing with me will attest to..)and tracked it down to two things:
1 - Rebuilt motor with new rings and pistons
2 - Blocked off PVC return to the intake manifold.
You can also check your plugs to see which cylinders are getting the oil burn.
The two above items solved my smoking (to the excitement of both racers and corner workers)
Anthony
NER ITA 86
Honda CRX Si
www.lisagardner.com/scrapbook
Speaking of race hours...what's the typical number of hours run before a rebuild? The bottom end technically has 200k on it but it has new rings and main bearings and has 175-180 psi on all cylinders. The original head on the CRX was junk so I did a core exchange with a newer civic and put in new seals and o-rings.Quote:
Originally posted by davew:
If you brought me a 10 year old honda w/ 185k miles on it and it checked out at 135psi I'd say it had decent compression....if you brought me and IT race car w/ 135psi I'd say it was time for a full rebuild. most race motors are rebuilt by the hours, so racing with a motor that is just shy of 200k miles boggles my mind...and you wonder why it might be smoking at upper rpms?? That said...an over rich condition can/will also wash down the cylinder walls and lead to blow-by past the rings. If you believe all else is well in the motor, that could be the culprit...but given the high mileage and the timing being off...well...maybe its time to freshen it up a bit?? if for no other reason so you have a bit more confidence in it while on the track...
-davew
-dw
[This message has been edited by Domino (edited January 07, 2003).]
Don't forget to tell them about different plugs in different cylinders http://Forums.ImprovedTouring.com/it/smile.gifQuote:
Originally posted by almracing:
I fought a smoking problem this past season (as those racing with me will attest to..)and tracked it down to two things:
1 - Rebuilt motor with new rings and pistons
2 - Blocked off PVC return to the intake manifold.
You can also check your plugs to see which cylinders are getting the oil burn.
The two above items solved my smoking (to the excitement of both racers and corner workers)
Anthony
NER ITA 86
Honda CRX Si
www.lisagardner.com/scrapbook
This really depends on your level of commitment and your budget. Top running national cars probably get the top end re-freshed every 12-15hrs and the bottom every 30 or so.....your average stock honda motor should run atleast 60k miles before beginning to loose power if treated well (not overheated or overrevved, regular oil changes, tuned correctly, etc...). The question is how long do you want to run a motor without inspecting it and refreshing it? Do you want it to run at its peak performance and know about problems before the happen, or do you just want to drive it just for fun...and fix it when it breaks?Quote:
Originally posted by Domino:
[B] Speaking of race hours...what's the typical number of hours run before a rebuild?
The same question applies to every component on your car...how long between caliper rebuilds? or Hubs? Struts? even tires for that matter...some people say they are good for 5-6 heat cycles max...some will say 5-6 seasons.... http://Forums.ImprovedTouring.com/it/wink.gif
-davew
-dw
Agreed.
However, I can tell on my car when it is rebuild time by how much oil accumulates in the dump tank during a session.
It gets progressively worse over time with some variations due to ambient temperature (the hotter, the more oil comes out).
While I own a leak down tester, I've never had to use it.
When the dump tank overflows during a session, it's time for a rebuild. If I keep running a few more weekends, I'm turned into a real EXXON VALDEZ.
It is always ring/cylinder bore wear in my case.
Compression testing is not much of a help unless you are diagnosing a sudden problem. Also, since compression is linked to cam timing, one car's readings are somewhat useless to those of another car owner; even without vernier cam pulleys, many things can effect and alter cam timing on engines.
Hence, a compression test goal is reading variations among the cylinders and not the gauge's reading for an individual cylinder.
Cheers.
135psi is not very good. Is this a 2nd gen d16a6? According to the Helm manual for this motor, minimal compression is 135psi. Nominal is 185psi. The d16a6 in my CRX has 120K on it and produced 185/180/180/180. May be a good time for you to rebuild the motor. Have you performed a leakdown test on the motor?
Don't forget to tell them about different plugs in different cylinders
Tom -
Didn't forget... just figured it was a good secret. It worked like a charm until I fixed the problem.
Anthony
ok guys,
well i decided to get the head rebuilt, hone the cylinders, and replace the rings. I am also opting to replace the bearings on teh connecting rods. Is there anything special i should know about doing this. The manual talks about differnt sizes and such, but the guy at the auto parts store didnt mention that.
I am going to try and just drop the pan, and pull the pistons out the top, and refresh, and drop back in. anyone done it this way?
An "in-car" cylinder hone job is not a good idea.
Honing creates some grit, and you are not going to be able to do as thorough a cleaning afterwards as you would mith the motor completely dissassembled.
Good luck
My thoughts: "Rebuilding the head might cause the rings to leak?" I don't see the logic there, unless you figure your head is absolutely toast, and you're making zero power.
You say you're down on compression, and timing is way off. Perhaps by 17ish degrees or so? Like the timing belt skipped a tooth? That will mess with your compression, depending on the engine and the cam events.
Last thought- rod bearings- Most Japanese mfg's select-fit rod bearings, so you have grades of crank journals, rod bores, and bearing thicknesses, the right combination of which gives very tight control over rod bearing clearance, which makes them live longer (and have better NVH when new). If you have your crank checked/polished/ground and your rods resized, all to within a couple microns of nominal, then you may be able to get by with one-size-fits-all rod bearings, but I sure wouldn't do that with my motor. I'd measure the daylights out of it (which can be done w/ the crank in the car sometimes, if you're set on leaving the crank in), use lots of fresh plastigage, and gets my bearings from my friendly neighborhood honda dealer, not Pep Boys. Better to spend a little extra time and $$ now, 'cause if you end up 0.001" or 0.004" clearance, you might as well kiss that rebuilt bottom end goodbye. Bearings are fussy critters, and you can't be too careful. At least in my opinion and experience.
Spend the money and buy the Honda bearings. When it's practical I always buy factory parts.Quote:
Originally posted by abower1:
[B]ok guys,
The manual talks about differnt sizes and such, but the guy at the auto parts store didnt mention that.
B]