Author Topic: CB750-Can you replace valve cover gasket with engine in frame? (Read 24603 times)

hevykevy420 · « **on:** November 09, 2006, 10:25:44 AM »

I've searched for this topic, and seem to be getting conflicting information. I don't need to remove the head, I just need to replace the valve cover gasket.

I've tried to remove most of the engine bolts, tilt engine down in the frame, to get the valve cover off, but can't seem to get the cover out, or tilt it forward enough to slide the cover out.

IS IT AT ALL POSSIBLE TO REPLACE THIS GASKET WITH THE ENGINE IN THE FRAME? (WITHOUT CUTTING FRAME?)

MY GIRLFRIEND IS NOT LOOKING FORWARD TO HELPING ME PULL THE ENGINE $:-\$ $:-\$ $:-\$

SORRY IF THIS IS A REPETITIVE QUESTION!!!!

andy750 · « **Reply #1 on:** November 09, 2006, 10:38:10 AM »

In a word -no

...Im pulling my engine tonight to tackle a similar problem.

good luck,
Andy

RRRToolSolutions · « **Reply #2 on:** November 09, 2006, 10:39:01 AM »

Sorry to b the one to tell you - No. It's a sad but true fact that the frame has to be poured around the engine like it is.

Here is a project for the brave -- or foolish (not sure which yet)

Regards,
Gordon

http://www.sohc4.us/forums/index.php?topic=15213.0

oldfart · « **Reply #3 on:** November 09, 2006, 12:14:46 PM »

Well, I can tell none of you guys worked in a Honda shop back in the 70s. It was common for techs back then to replace the valve cover gasket on the CB750 with the engine in the frame, and beat Honda up on the factory flat rate at the same time, of course. So, yes, it can be done. The gasket will spread over the valve cover, and as long as too much scraping of the head isn't necessary (to remove the old gasket) then a new one can in fact be put on in the frame. I have done it, and I have seen it done. Unfortunately, that is about all you can do.

Geeto67 · « **Reply #4 on:** November 09, 2006, 01:20:08 PM »

Quote from: oldfart on November 09, 2006, 12:14:46 PM

Well, I can tell none of you guys worked in a Honda shop back in the 70s. It was common for techs back then to replace the valve cover gasket on the CB750 with the engine in the frame, and beat Honda up on the factory flat rate at the same time, of course. So, yes, it can be done. The gasket will spread over the valve cover, and as long as too much scraping of the head isn't necessary (to remove the old gasket) then a new one can in fact be put on in the frame. I have done it, and I have seen it done. Unfortunately, that is about all you can do.

I've seen it done with gasket sealer like honda bond or the right stuff but never with a cut to fit gasket - too easy to rip trying to clear the valve train.

oldfart · « **Reply #5 on:** November 09, 2006, 05:22:08 PM »

Well, it's the actual gasket I am talking about, and it isn't the valve train that is the hurdle, it's stretching the gasket over the valve cover itself. The gasket is quite narrow of course and easy to break because of it. But it can be done, and Honda techs of 70s like yours truly did it whenever necessary, and enjoyed gaining the extra 2 plus hours (factory flat rate is an even 3.0 hours for that job). American Honda knew we were doing that, but never changed the flat rate. Of course, to their credit, not many engines had leaking valve cover gaskets under the warranty either. Another bike, the early four-cylinder Gold Wing offered a similar boost to the technicians retirement account. The GL1000 neutral switch used to quit working, and a lot of them did it. Experienced techs found that they could replace it without removing the engine from the frame like the manual called for. This one however Honda took notice of and consequently reduced the flat rate to match the new technique, which consisted solely of using a long lever to pry the frame away from the engine slightly (with the engine bolts out). As I say, stuff like this is ancient history to old crusty Honda techs.

And the CB750 SOHC valve cover gasket can indeed be replaced without removing the engine, with no ill effects.

scondon · « **Reply #6 on:** November 09, 2006, 06:10:25 PM »

Pure Gold

I'm gonna try it out on my Daily Rider after I'm done putting the current project together. Fortunately I've got a couple gaskets laying about in case one rips.

RRRToolSolutions · « **Reply #7 on:** November 09, 2006, 06:17:42 PM »

Are you guys using 1104 bond on the gaskets? I just cut my frame and peeled the cover off so I could spend an hour cleaning off the gasket goo...I darn sure wouldn't scrape the gasket without first plugging all of the oil return holes and passages. I had to replace the 6 sealing rubbers under the towers also, but my head cover left gasket material stuck to both the head and the cover. How do you keep it out of the engine and get it cleaned-up after scraping with this cover-in-place repair?

What about your clutch covers, are you using 1104 bond on both sides? I'm going into my clutch for a 3rd time in 1 month and don't like the goo removal.

I need to know these things...

bwaller · « **Reply #8 on:** November 09, 2006, 08:11:53 PM »

I always use a little 1104 on those sealing rubbers but never needed to on the valve or the clutch cover. With clean undamaged surfaces always found a new gasket was enough.

hevykevy420 · « **Reply #9 on:** November 10, 2006, 07:22:55 AM »

Quote from: Ilbikes on November 09, 2006, 06:17:42 PM

Are you guys using 1104 bond on the gaskets? I just cut my frame and peeled the cover off so I could spend an hour cleaning off the gasket goo...I darn sure wouldn't scrape the gasket without first plugging all of the oil return holes and passages. I had to replace the 6 sealing rubbers under the towers also, but my head cover left gasket material stuck to both the head and the cover. How do you keep it out of the engine and get it cleaned-up after scraping with this cover-in-place repair?

What about your clutch covers, are you using 1104 bond on both sides? I'm going into my clutch for a 3rd time in 1 month and don't like the goo removal.

I need to know these things...

Ilbikes- I've been battling this valve cover leak for some time. After 836 rebuild, I used all new gaskets, but didn't use any gasket sealer on the valve cover (was told i didn't need it). Valve cover proceeded to leak immediately during and after break in. I loosened up the cover, and inserted some non-hardening permatex (the black stuff) between the gasket, head, and valve cover. I still had leaks. To answer you question, when I cleaned the old gasket goo out with the engine in the frame, i carefully tried to genly scrape out the remaining goo from the surfaces away from the inside of the engine. (I've since tried Permatex high temp silicone, the red stuff, but STILL had a leak.) What I would recommend to you, is to drop your oil pan soon after you remove the old gasket material, and clean out whatever you find from there, and also the oil filter housing. I had a TON of the non-hardening sealer in there, even though I was careful. The engine still runs great, and I feel better I got it out of there!

I am now attempting to use Hondabond 4 on a new gasket, to see if I can stop the darn leak!

hevykevy420 · « **Reply #10 on:** November 10, 2006, 08:01:16 AM »

Old Fart-

Thanks for the tip! I never thought to slip the gasket OVER the cover. I'll give this method a try, hopefully I don't rip/tear the gasket, it takes a week for the Honda dealership to get one delivered!

RRRToolSolutions · « **Reply #11 on:** November 10, 2006, 11:35:29 AM »

I hate leaks. This is why I have been using the 1104 bond on everything except base gaskets and head gaskets. This trash/goo/gasket mess is why I wanted to pull the cover completely. I plugged all of the holes and stuffed clean towels down the chain opening while I cleaned the surface spotless (as shown). I then use lacquar thinner to really clean the surfaces so the new 1104 will seal. If there is a way to absolutely, positively stop it from leaking without sealent, I'd love to know the tricks. I'm dreading the clean-up from the clutch cover more than the work to replace the clutch compnoents for the 3rd time.

Thanks for the inputs.

Regards,
Gordon

hevykevy420 · « **Reply #12 on:** November 10, 2006, 11:58:36 AM »

Gordon- I hear you!!! I'd love to know how to not use any sealant as well!!! I am frustrated with this stupid leak, especially after how long it took to completely rebuild the engine, paint the frame, etc., etc.

And i have a stupid gasket leaking that can't be easily removed...

I just picked up the cover gasket from the dealer...it does appear to be better quality than what came in my "top end gasket kit". maybe that has something to do with it...all i know is I'm running out of sealant options...just picked up some 1104 instead of Hondabond since it appears to be the sealant of choice.

good luck to you, let me know how it turns out!

RRRToolSolutions · « **Reply #13 on:** November 10, 2006, 03:41:43 PM »

I can tell you now - the head cover leak is gone. I've put 100 + miles on the bike since the frame mod and sealing rubbers were done. I coated both sides of the fatory Honda gasket with 1104 (no more aftermarket sealing gaskets for me unless the factory ones aren't available). I've been bit now several times when buying those kits. The head cover gasket I took off stuck to both parts and was still leaking - cheap PNM "Athena" gaskets won't grace my door again. I know it says OEM, but none of them really fit well and the sealing rubbers didn't seal in the oil nor did the cover gasket stop the seepage in the front. I had the same issues with a recent H2 project and winded up taking the clutch cover off and using a factory gasket to seal-up the leak. # times the cost - 10 times the better gasket "it don't leak".

How many put their clutch covers on without sealant? I'm sure I'll be in that thing again.

Thanks,
Gordon

hevykevy420 · « **Reply #14 on:** November 13, 2006, 08:57:38 AM »

UPDATE-

The GOOD: I was able to replace the valve cover gasket with the engine in the frame by carefully spreading the new gasket OVER the cover, then applying a thin amount of 1104 to both sides of the gasket. Let it be known that it is possible to replace this gasket engine in the frame, thanks Old Fart!! I let it sit for 24 hours then test drove. No leaks from the cover!! I'm exstatic!! UNTIL

The BAD: I pull the bike into the garage after test drive, and shut down with a big smile on my face. But, when I check out the engine, OIL IS NOW LITERALLY STREAMING DOWN THE FRONT OF THE ENGINE, AND ONTO THE FLOOR, from what appears to be the head area. Before I replaced the valve cover gasket, I did not have ANY leaks from anything except the valve cover.

I checked compression with the warm engine, giving full throttle but with engine switch in OFF position, and I get 130psi. I added a tablespoon of oil or two and I get 190psi. I am on a 836 rebuild with no more than maybe 1-2K miles on the rebuild. If these compression figures are low, I can't tell by riding, engine "feels" good.

I don't have anything connected to the valve cover breather, and the crankcase breather routes back to the oil tank, which I believe to be proper.

CAN ANYONE HELP ME OUT WITH ADVICE?? I am at the end of the line with my patience with this bike. For the amount of time and $$$ + blood sweat and tears I've poured on this bike, I should have a good running reliable bike at this point. To say I'm frustrated or close to giving up, is an understatement. I don't have the patience to rebuild this engine again, it will just end up a bunch of boxes with expensive engine parts in them. At this point I am ready to get rid of this bike, even though I've invested tons of money and effort into it, and my PITA will be someone else's gain.

If anyone can help me out, I'd be extremely grateful.

andy750 · « **Reply #15 on:** November 13, 2006, 09:14:23 AM »

Sorry to hear about your massive oil leak and I know its no consolation but the same thing happened to me...only I had removed the engine from the frame and took a long time in rebuilding the top end. I put the engine back in the frame, assembled the rest and took for a test drive. I only went 1/4 mile and then noticed the flood of oil coming from the front - by the sounds of it same place as yours. I was also devasted and didnt think I could pull the engine again (will be the 5th or 6th time now).....but I have done so, and its now in the hands of a very well known expert mechanic from this site so Im happy for that.....at the end of the day you WILL fix this and the frustration now will be replaced by that smile on your face again. Not much technical help I know but I KNOW your pain!

good luck and keep us posted,
cheers
Andy

P.S. Could it be the oil seals under the towers? I doubt it as you wouldnt have removed the cam but thats all I can think of...unless you stripped a bolt/stud on reassembly as I seem to have did

RRRToolSolutions · « **Reply #16 on:** November 13, 2006, 09:25:57 AM »

Kev, are you ready to do the frame mods? Don't throw the bike out. Look at the link I provided up at the top of this thread. My new 836 build had 200 miles on it and I had oil leaking from the rubber sealers under the cam towers and my cover gasket was leaking at the rear. Cutting that frame and making a removable member was the best option, but I also wanted to have something as strong and as safe as the original.

I spent 2 hours packing and plugging all of the oil return holes and removing goo/gasket crud. I will not be trying to change gaskets without this precaution - I've got too much invested. Full removal of the cover, the cam, the towers, and the head is now easy afternoon task. I can do more head work, re-ring, re-sleeve, whatever all without pulling the engine. I'm overseas for another week, but when I get back, I'll be glad to help and get those pieces machined for you and anyone else who wants to do it.

Regards,
Gordon

hevykevy420 · « **Reply #17 on:** November 13, 2006, 09:41:45 AM »

Gordon-

If you could make me those parts, I will definitely take you up on it! I can't really tear down again, I have nobody to help me with this engine.

How can I tell If the cam towers are leaking? Where does this oil leak out of the engine? I have suspected too much crankcase pressure is causing the leaks, why else would the repair of one gasket cause a leak somewhere else? I am worried even if I rebuild, I'll still have leaks if it is excessive crankcase pressure related...

I did notice one of the right side cam tower nuts was loose, I snugged it up before replacing the gasket. Not sure if this means anything?

scondon · « **Reply #18 on:** November 13, 2006, 11:02:59 AM »

Leaks from under the cam towers will usally show up in the spark plug areas up front and also in between the lower fins of the cylinder head on the side of the engine(just above the head gasket).

I wouldn't think that removing the valve cover would disturb any seals below it and also that fixing the cover leak wouldn't create more pressure to cause a leak elsewhere. You do state that one of your outer cam tower bolts was loose and that you retightened it. If any of your inner tower bolts are not properly torqued down this could cause a leak under the towers.

Maybe you can remove the 8 tappet covers and get a peek inside to confirm that none of the other cam tower bolts have backed out. This could cause leaks and premature cam wear/failure.

Before becoming too alarmed it is best to identify EXACTLY where the oil leak is coming from. Oil flows mostly downward and where it pools and is most evident on the outside of the motor is not always near where the leak source is.

If it's any consolation, I had to pull my first two engines a total of five times for one reason or another. It feels awful at first to think of going through all that labor again, but once resigned to it it goes pretty quickly and more is learned in the process. The only help needed is an extra hand for 20 minutes to remove the engine and even a friendly neighbor can help.

Here's hoping that oil leak traces back to a valve cover bolt that got missed in the torquing process

RRRToolSolutions · « **Reply #19 on:** November 13, 2006, 05:22:21 PM »

Kevin, just as Scondon stated - I knew my rubber seals under the towers were leaking because I had traces of oil puddling around the spark plug bases. It would seep out from under the cam tower plugs (made to seal the elements out beneath them and over the fins. These allow access to 6 of the head nuts). Anyway, I'd used Athena seals that came with the gasket kit and no sealer since adding 1104 bond to the sealing edges is not in the factory manual - I had leaks. There is no pressure on these if your top vent is open and the hose is clean. The only pressure would be crankcase pressure created by the pistons going downward (PCV) sort of. This whole leak issue under those towers and the cylinder cover is gravity oil returning to the crankcase.

I suspect that your leak is not from a new source. It's still the cover seal, but instead of it coming out of the outer surface, it's now leaking above/behind one of the sparkplug reliefs in the cover and is flooding the sparkplug area of the head and then pouring down the front. Perhaps trash or a buckle in your gasket in that recessed are is allowing more oil than before to find it's way under that gasket and making it's messy, stinking, burning journey down your head and onto the front of the engine. I also don't believe one repair would cause another leak - my bet is you really haven't fixed it by replacing the gasket - yet.

There is hope. It comes in the form of a Portaband and a TIG welder.

Scondon, I had a tough time getting my bare, powdercoated frame carefully manuvered to fit over my engine with it on it's side, sitting on a pillow and table top and all frame pieces covered in multiple layers of blue masking tape. I can't imagine being able to get the engine out/in the frame without scratching the frame or a freshly painted engine. Can it be done? Tearing mine down to a bare frame to get the engine "poured" out/in was the dreaded excercise. I'm sorry to make this a big issue, but I was so pissed when I'd spent all of the time and money doing it right and then have oil coming out of 6 seals and a simple cover leaking in several places.....real bummer.

Hope we've helped you Kevin -

Regards,
Gordon

scondon · « **Reply #20 on:** November 13, 2006, 06:32:01 PM »

Quote from: Ilbikes on November 13, 2006, 05:22:21 PM

Scondon, I had a tough time getting my bare, powdercoated frame carefully manuvered to fit over my engine with it on it's side, sitting on a pillow and table top and all frame pieces covered in multiple layers of blue masking tape. I can't imagine being able to get the engine out/in the frame without scratching the frame or a freshly painted engine. Can it be done? Tearing mine down to a bare frame to get the engine "poured" out/in was the dreaded excercise. I'm sorry to make this a big issue, but I was so pissed when I'd spent all of the time and money doing it right and then have oil coming out of 6 seals and a simple cover leaking in several places.....real bummer.

Hope we've helped you Kevin -

Regards,
Gordon

Yeah, I had a tough time trying the bare frame method too. Guess I'm just used to maneuvring the engine in and out of an upright bike by now. I've got a powder coated frame and painted engine too and found that thin cloth shop towels secured to the frame rails by that blue masking tape you mention works pretty well at avoiding scrapes and scratches. Lift the engine and rest it halfway onto the bottom frame, then have one person on each side of the bike while lifting and maneuvering it the rest of the way. The trick is to go slow and methodically and not let the engine drag across any part of the frame. Move a bit at a time then let it rest on the towels while you scout out the next clearance issue.

OK, back to 'kevy's leak. Gordon may have it with the "buckled" gasket thought. The last time I pulled a motor was because oil was gushing out. Not just weeping or seeping but GUSHING out. Turns out my valve cover gasket was pushed into the engine upon reassembly and only 1/16" was left between the mating surfaces in one area. Once that little bit of gasket failed there was a a clear opening for hot oil to gush out of.

hevykevy420 · « **Reply #21 on:** November 16, 2006, 10:21:25 AM »

sconden- I looked at the valve cover gasket very closely for a "buckling" and I did notice that the gasket was not perfectly centered around the section of the cover that tightly wraps around the front of the cam chain, on the front center of the cover, right by the cam chain sprocket. i had a tough time getting the gasket aligned around the inset areas by the #2 and #3 plugs upon reassembly...I did the best I could without breaking the gasket. It just didn't seem to fit perfectly in this area.

I'm not getting any oil leaking at this point, but I'm wondering if a slight misalignment on the gasket could cause a leak at the cam towers?

I'm just trying process of elimination, I'm almost certain it is not the head gasket, and now valve cover is tight and dry as a whistle after replacement, but oil pouring down front of head area...

scondon · « **Reply #22 on:** November 16, 2006, 11:43:59 PM »

I don't see how the valve cover gasket could interfere with anything and cause a major leak, especially to the cam towers as those seals are far from the gasket area. If your valve cover gasket is not leaking I'd move on to anything else that was touched during the procedure.

Oil leaks can be deceiving as to their origin so best to wash away all traces of oil from the front/top of your motor, then start the motor and stop it as soon as you see oil and trace the leak upwards to the origin. If you're leaking so much oil that it's leaving drops on the ground after a twenty minute ride then it may not be the tower seals as these tend to "seep" oil onto the upper fins slowly, generally, not sudden and extreme leaking

If you removed the 8 tappet covers during your gasket change you can check and see if any cracked when replaced. Easy to overlook, but oil would certainly flow out if one cracked and the majority of oil would end up on the fins and spark recesses.

Retrace your work and check the areas that you worked on. Clean the engine and see if you can rule out the simple stuff first.

bryanj · « **Reply #23 on:** November 18, 2006, 08:43:42 AM »

Dont forget the tach drive seal in all this!

pete75 · « **Reply #24 on:** November 18, 2006, 01:27:27 PM »

Quote from: Ilbikes on November 09, 2006, 06:17:42 PM

Are you guys using 1104 bond on the gaskets? I just cut my frame and peeled the cover off so I could spend an hour cleaning off the gasket goo...I darn sure wouldn't scrape the gasket without first plugging all of the oil return holes and passages. I had to replace the 6 sealing rubbers under the towers also, but my head cover left gasket material stuck to both the head and the cover. How do you keep it out of the engine and get it cleaned-up after scraping with this cover-in-place repair?

What about your clutch covers, are you using 1104 bond on both sides? I'm going into my clutch for a 3rd time in 1 month and don't like the goo removal.

I need to know these things...

Lovely pic - what a nice clean motor..........

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Author Topic: CB750-Can you replace valve cover gasket with engine in frame? (Read 24603 times)

pete75