UOA's and valve clearances

Messages
44
Location
pennsylvania
Honda recommends 105000 mile valve clearance adjustments on many of its 4 cylinder engines, including the 1.7 in my 05 Civic. There has been a school of thought that this is possibly far too long. In fact, severe damage to engines in Gen 1 CRVs has been pretty well documented in some forums due to burnt valves. One possible approch is just to adjust the valves earlier, which is not super expensive but not cheap either and possibly not needed. Would UOA's catch it if the valves begin to tighten up? What would one look for?
 
Messages
4,478
Location
Southern California
I'm not qualified to predict any particular UOA wear metal spike that would indicate tight valves. There'd be little in the way of symptoms until valves failed to seat properly. The engine would idle rough. By that time, valves would also already be burned. (Hello, head rebuild.) In my humble opinion, the smart money would be on just prophylactically adjusting the valves every 15,000-20,000 miles. I did that maintenance on my Accord myself. (Now, <i>that's</i> cheap!) The service manual specified adjusting the valves when the engine is cold - very convenieint for the fourth-degree burn shy, such as myself, leery about roasting their irreplaceable fingers on a hot engine.
 

dinosauract

Thread starter
Messages
44
Location
pennsylvania
That's probably what I'll do. Even a 30k interval should be pretty safe. In the manual, they say to adjust the valves only if noisy, which would indicate a loose clearance. The tight situation, by far the most dangerous, wouldn't lead to noise.
 
Messages
1,294
Location
Western Washington
My '95 Accord I-4 originally recommended adjusting valve lash every 15k miles. This turned out to be too often, so it was changed to 30k. I went 40k last time and they weren't very far out of spec. I think I'm going to go 30k-40k from now on, depending on how far out of spec they are each time.
 
Messages
4,499
Location
Massachusetts
quote:
Originally posted by Gary in Sandy Eggo: Why would ANY auto manufacturer within the last 50 years build an engine without hydraulic lifters ? Regards, Gary in Sandy Eggo
The cam(s) rides above the valves.
 
Messages
177
Location
Salem,Oregon
Zaedock; if BMW can build overhead cam engines with hydraulic tappets that do not need to be adjusted, why can't Honda? I believe that's what Gary in Sandy Eggo meant.
 
Messages
4,499
Location
Massachusetts
quote:
Originally posted by Ken E.: Zaedock; if BMW can build overhead cam engines with hydraulic tappets that do not need to be adjusted, why can't Honda? I believe that's what Gary in Sandy Eggo meant.
I guess they could. Then your Honda Civic would cost 50 grand too. The bottom line is as Master ACid said : efficientcy. The OHC with adjustable rocker arm also fits into a much smaller package and is cheaper to produce. I adjust the valves in my 'Zuki powered Tracker every 30K miles/or if they're noisy. It's not too difficult a job. I think oil quality has stretched out valve adjustment intervals over the years.
 
Messages
6,171
Location
Santa Barbara, CA
Umm, Mazda has DOHC engines with hydraulic lash adjusters. [I dont know] They have for over a decade. I'm sure there's other examples I'm not aware of also. For my GFs '96 Civic, the owners manual and shop manual say to adjust the valves at 30k ONLY. No further adjustments after that.
 
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2,724
Location
Herndon, Virginia
My 92 Elantra (Mits 1.6 DOHC) had hydraulic adjusted lifters, my 85 NightHawk S 700cc had em, and my new 2005 Hyundai 1.6 has em. Cheaper cars they don't make than this Hyundai. I had no idea any car had adjustable valves these days.
 
Messages
286
Location
the Netherlands
When you want a VTEC system you need more then 1 rocker arm per valve. So the cam cant be above the valve. Thats one reason I think Honda doesn't use the hydrolic tappets. Maybe also because with rocker arms you can have every valve at a different angle. What I mean is they all point outwards from the same centrepoint somewhere in the cylinder. The cylinder head then can be hemisferic and the valves follow that profile so they all point outwards.(I hope I've discribed it ok). They also could use bigger valves because of that. I dont know if that is used in car engines, I DO know it was used in motorcycles, I remember a brochure from Honda about that.
 
Messages
10,906
Location
Nokesville, VA
quote:
GM's Ecotec DOHC also has hydraulic lash adjusters:
So does Ford's now out-of-production 2.0L DOHC Zetec engine (introduced in 1995) and their 2.5L/3.0L DOHC Duratec V6 engines. EDIT: The later versions of the Zetec have variable valve timing on the exhaust cam for emissions control (provides an EGR effect). Even their old 1.9L/2.0L SOHC engines (used in the Escort, a really expensive car [Razz] ) have hydraulic lash adjusters..
 
Messages
74
Location
Miami, Fl
Ducati motorcycle. Desmodromic valves. NO valve springs, two shim adjusted rockers per valve! Real pain to adjust. Main reason for adjustable valves is precision. High revving engines must have very precise opening and closing of valves to obtain max performance, the hydraulic systems have some slack (for want of a better word)which doesn't allow as accurate a valve opening as adjustable valves.
 
Messages
1,203
Location
Oregon
Most Toyota's and Honda's use solid valve lifters because the are more Efficient from a performance stand point than hydraulic lifters. Mostly from reduced valve train weight. But there are other advantages in the area of cam lobe profile. More precision control of valve opening and closing events. You also don't have to worry about hydraulic lifter pump up with solid lifter. Ford and Chevy know this also. That is why all their true High performance muscle cars in the 60s and early 70s used solid lifters. There is a few bikes that do use hydraulic lifters but none of these are considered high performance bikes going by the horsepower per cc.
 
Messages
4,499
Location
Massachusetts
quote:
Originally posted by Zaedock:
quote:
Originally posted by Ken E.: Zaedock; if BMW can build overhead cam engines with hydraulic tappets that do not need to be adjusted, why can't Honda? I believe that's what Gary in Sandy Eggo meant.
I guess they could. Then your Honda Civic would cost 50 grand too.

Ok, we're going to learn a new word today. It's called SARCASM. [Duh!]
 
Messages
23,591
quote:
I guess they could. Then your Honda Civic would cost 50 grand too.
My 1980 VW Scirocco already had hydraulic valve lifters in its 1.8l OHC engine. That engine was in production since 1974. All my Euro cars had hydraulic lifters in OHC engines. None of those cars cost 50 grand. [Smile] PS: Honda VTEC engines have used hydraulic lifters for over 20 years.
 
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