PDA

View Full Version : Cheap fix for the burnt valve problem.


akhom
03-31-2007, 01:27 AM
I notice alot of the members are replacing cylinder heads and spending thousands of dollars.

I have a 99 CR-V. Back in Dec of 2005 I noticed the problem with my motor. Check engine light and misfire ETC..
So it was a burnt valve. I drove on it for a year and finally in Dec 2006 I replaced it. I was able to drive it on a burnt valve for so long was because I have a manual and can keep the revs up and prevent it from stalling. So you can guess the amount of damage on the valve and valve seat as the thing would not hold an idle. In fact 1/3 of my valve was gone. I'll post photos later.

Now I have built Honda B series motors in the past and still do. So I salvage some intake valves from a left over P75 94-01 Integra LS head. I took apart my head. Pulled out 2 valves and check the valve seats. Well the valve seats are fine. So is the rest of the head. So I went ahead and installed the 2 used valves I salvaged. Put everything back together and started it up. Everything ran geat. No problems. Keep in mind I just slapped the valves in. No lapping or valve job.

So what I'm telling you is in most cases you do not need to replace the head. All you need is to buy a few exhaust valves. If your valve seats are damamged any head repair shop / machine shop can do a 3 angle valve job for about 150.00 dollars and they will install you new valve and lap them in.

Parts needed are exhaust valves and a head gasket. Leave the intake maniold on the head so you do not need a new intake manifold gasket or have to clean up the old gasket.

Good tool to have beside the basic to remove everything is a Dual over head Cam valve installation tool kit. Great tool to have then your trying compressing the valve springs to reinstall the valve keepers.

My total out of pocket cost 35.00 for a cheapo aftermarket headgasket and about 4 hours of time.

I hope this info helps someone. Get a Helms service manual for the CR-V and you can do any of your own work. It is not very hard.

Len
03-31-2007, 08:20 AM
I'm glad it worked out fine for you. I hope it lasts. Iíve heard about it being done on other cars.
Have you done any compression/leak down tests before and/or after? Just curious.

mdugan7000
03-31-2007, 08:31 AM
Most people cannot do this though. They either don't have the skills, tools or time to get it done. I do agree though that way too many heads are being replaced at a very high cost. I don't understand why more people don't use an independent mechanic that will essentially do what you are saying. I would at least buy new valves and probably replace all 8 exhaust valves since the head would already be off.

akhom
03-31-2007, 09:20 AM
Yes I did do a compression and leakdown before I took apart the head.
Cylinder #4 was holding very low. I forget what the other 3 cylinders held but they were all very close to each other within 5 PSI. As for leakage I was able to feel the air flow out the muffler in the back on cylinder #4.

After the put it all back I have not done any compression or leakdown. However it now drives fine and no check engine lights. This CR-V is my work horse. Drive all around town picking up and dropping off parts. I put about 30K on it a year.

As for changing out the other 6 exhaust valve, it is a very good idea. However I did not care because I am currently building another motor for the CR-V.

What I did to fix the burnt valve problem can be done at any generic auto mechanic shop for under 1000.00 It should only cost a litttle more than a head gasket job. Shop around.

Len
03-31-2007, 09:23 AM
Great info. Thanks.

steelhead
03-31-2007, 01:32 PM
great job with burned valves

but, will not help with the major head problem with Honda B20s, valve seat regression which results in leakage and eventual burning of the valve lip....have to fix the seats also with a grind job....

just check and adjust every 30k, use a high quality oil with lots of anti wear additives such as Mobil 1 or Chevron Supreme Havoline, change often and the valve train/engine will outlast the body....

akhom
04-01-2007, 01:44 AM
So why do the B20 motor have this problem? THey use the P75 Head with is the same as the 94-01 Integra Non VTEC head. The Integra do not have this problem. Why do the CR-V seem to always have burnt valves?

Thanks
Andy

steelhead
04-01-2007, 08:01 AM
probably head source in JA....Honda outsources everything in their manufacturing....probably 10 small mom and pop operations making CRV heads...

dmlevel.com
04-27-2007, 10:51 AM
same symptoms... 1999 140K miles
Auto zone gave me these codes:
p0300
p0301
p0302
p0303
p0304
they all mean cylinder misfire. but does it meen, i need or need to clean my fuel injectors, is it burnt valves? vacum? fuel filter?

'Curly Q Links'
05-30-2007, 10:59 AM
So why do the B20 motor have this problem? THey use the P75 Head with is the same as the 94-01 Integra Non VTEC head. The Integra do not have this problem. Why do the CR-V seem to always have burnt valves?

The Integra does have this problem, but I think the older Integra owner's manual may have been truthful about the correct adjustment interval . . .

Do you know what the Teg manual says ?

:?:

mdugan7000
05-30-2007, 11:08 AM
The Integra does have this problem, but I think the older Integra owner's manual may have been truthful about the correct adjustment interval . . .

Do you know what the Teg manual says ?

:?:Interesting. I just looked at the 94 Integra maintenance schedule and it calls for valve adjustments every 15k miles!

'Curly Q Links'
05-30-2007, 02:13 PM
Interesting. I just looked at the 94 Integra maintenance schedule and it calls for valve adjustments every 15k miles!

No wonder . . . The Integra do not have this problem. :shock:

Amazing what a little Truth in Advertising will do for your product. :rolleyes: