Topic: Damage from too much oil...

[Jonm99]

Hi guys,

I just got my bike back from the garage after having replaced my gear (had a problem with first, all good now). On my first ride out after about 15 minutes the engine died (in the middle of the freeway) and the engine bay was smoking (mainly on the right side). I let the bike cool down for a half hour or so and slowly made my way home. after that ride I checked the oil level to see if that was the culprit, and indeed, there was about 600ml of oil beyond the top indicator of the stick. I drained out the excess, but now have two new symptoms... a light leak from the gasket head in two areas (around plugs 3 and 4) and a knocking sound from the engine (top right side, increases with rpm increase, clutch in, clutch out, doesn't matter). No noticeable change to power, the bike runs great. I adjusted the valves (they were a bit off spec for cylinders 3 and 4), adjusted the cam chain, and swapped in new plugs. I am assuming that the excess oil caused the head gasket to blow, but is this related to the knocking noise (it was not present before I took the bike to the garage)? Next item to check will be the headers. I provided the garage with new crush washers, but maybe they clamped them down too much?

Any help will be greatly appreciated.
Jonathan

1977 cb750k with original airbox, slow jets=35, main jets=120, Delkevic 4in1 headers, 18" Cone engineering QC muffler, 7" headlight, dynatek ignition, ss r/r, clip ons, and ebc front brake rotor.

[pjlogue]

Not sure what you mean by "garage" or what work they did on your bike.  If it involved opening the engine case I would be quite worried.  The knocking is not good and the fact you said you needed to adjust the valve lash on 3 & 4 makes me think you had oil starvation on the top end because of either a clogged oil passage to the head on that side or oil foaming.

I would not run the engine until you find out what the cause of the knocking is.  You should pull the oil filter housing and look for metal filings in the filter and housing.

-P.

[69cb750]

Any extra oil over tank capacity gets pushed out of the tank onto the road, no damage occurs.

[ekpent]

Any extra oil over tank capacity gets pushed out of the tank onto the road, no damage occurs.

+1 - cross the oil overfilled cause off the list on a 750 with an external oil tank. Oil pump takes what it needs and circulates it back when working correctly. In my earlier days I would just dump all 4 qts in on an oil change and it did not overflow from the tank. When you checked the valves was everything nice and oily on both sides of the cam/tappets area ?

[Jonm99]

Roger excess oil not being the culprit. That said, after draining the excess oil the engine stopped overheating...but maybe a coincidence?

Not sure what nice and oily would be, but they were definitely not dry. Can a valve somehow tighten on its own or is the conclusion that they adjusted my valves while they were at it (didn't ask them to) and did a poor job?

I pulled the oil filter, and while I did not find anything unusual in the filter or housing, when I dumped the oil into a pan, I did see what looks like metal shavings (see video here: https://photos.app.goo.gl/2S6jwKqKDnAS4SBS8).

I also removed and reinstalled the headers (thinking maybe it was an air leak).

Took it for another (short) ride, and the knocking noise seems to have gone away... but maybe it's just wishful thinking. Here is what it sounds like now https://photos.app.goo.gl/anWE5gvqTHvu7aE67. Unfortunately I don't have a sound bite from before.

In summary, is it possible that too little clearance on the #4 valve caused it to overheat, and ultimately shave some metal, which is what I saw in the filter? And now that I've adjusted the clearance, we are good to go (minus some damage that cannot / or is not worth fixing)?

Thanks,
Jonathan

[scottly]

Any extra oil over tank capacity gets pushed out of the tank onto the road, no damage occurs.

+1

The K7 oil tank doesn't have the vent tube that the earlier tanks had, so any extra oil can't get pushed out onto the road. Still, it shouldn't cause any damage. After the latest ride, what was the oil level in the tank?

[Jonm99]

Oh...so I suppose that explains the head gasket leak.

Knocking is still there unfortunately, guess it was just wishful thinking. Soundbite here: https://photos.app.goo.gl/J1vindZcn6fTB3EbA

As for the oil level, after dumping whatever was in the filter housing, I am at about 1.5cm from the top of the tank indicator.

So where does that leave us?

[pjlogue]

What exactly did the "garage" do to the bike?  You mentioned a problem with first, what problem did you have?

If the engine case was opened and the garage used silicone seal gasket inside the engine (or had dirt get inside the engine) that can cause big problems for the oil feed to the top end.  The oil for the cam passes through small restrictors that limit the flow so the bottom end (crank bearings) get enough oil.  If the restrictors are clogged the cam shaft bearings will quickly be ruined.

You can pull the valve adjuster caps {#'s 1 & 4) and look inside the valve cover while the engine is running (have a rag ready) and see if you can see oil  flowing.  If the rockers and cam appear dry then a blocked oil restrictor is the problem. 

-P.

[Jonm99]

1st gear was jumping out of gear (into neutral) at around 3-4k RPM. They swapped out the entire gear for another one I gave them. At least the gear works smoothly now... 

There's definitely SOME oil getting through as when I adjusted the valves, they were not dry. But I will check again with the engine running and report back.

Thanks,
J

[enwri]

I'm not sure you should run that anymore, that oil has an awful lot of glitter in it. It may be eating a cam lobe or two. It'll be in the mains and big ends now as well.

[Jonm99]

You can pull the valve adjuster caps {#'s 1 & 4) and look inside the valve cover while the engine is running (have a rag ready) and see if you can see oil  flowing.  If the rockers and cam appear dry then a blocked oil restrictor is the problem. 

-P.

Thanks P, this was a good recommendation and indeed.... Valve 1 is spitting out quite a bit of oil (https://photos.app.goo.gl/Sg1oo1RD6unnWiPo8) while valve 4 much less (https://photos.app.goo.gl/Sg1oo1RD6unnWiPo8). It's not dry, but it looks like we've found the issue. To be sure, this is unrelated to the clearance on the tappet? If not, than I guess the next step is to open the cases again and look for damage... Will it necessarily be noticeable to the naked eye or do I need to measure tolerances on all moving parts?

Thanks again guys, immensely helpful!
Jonathan

[pjlogue]

Before opening the cases I would pull the cover off the cam, then pull the cam out and check the bearings and journal.  If you see galling and heavy wear then I would pull the head and inspect the oil restrictors.  More than likely one is clogged. 

The oil restrictors clog easily if RTV sealant gets into the oil passages.  Other dirt can clog them as well.  When the garage split the cases they may have sealed them on reassembly using RTV and it got into the oil passage that feeds the top end.  Loose dirt and bits of RTV in the sump should be caught by the oil filter.  RTV around the oil feed passages that go to the top end will cause problems.

-P.

[Jonm99]

You guys were spot on! Looks like damage to the camshaft (bottom holder?) and more, including melted puck from oil starvation to the top right of the engine. And indeed, mechanic used a silicone based hardening sealant "that they use on all bikes". They are adamant about that not being the source of the problem, but rather gunk that somehow made its way to the top. See attached images.

So....
1. Why do I have so much gunk in the head (again, it was clean 1k ago)?
2. How do I make sure that they have resolved the source of the issue (finding the silicon beads, removing all the silicon from the cases, etc) and not just the symptoms?
3. It would seem like quite the coincidence that the engine was entirely redone (by me) less than 1k km ago, was running super smooth, and the first ride after they split the cases, engine is smoking and dies on the freeway, but that it would nevertheless be unrelated to their work. Any help in demonstrating the logic, or lack of, to this argument?

*first 3 images are from the first time they opened the engine. Rest are from the second time.

Thanks again,
Jonathan

[CycleRanger]

That looks like black RTV all around the edges of the case...
If they're using that on all the bikes they're doing it wrong.

[Jerry Rxman Griffin aka MuthaF'er]

In the next to last picture of the top of the head, what is that plug looking thing around the oil jet's o-ring? I am seeing your picture correctly?

[bryanj]

You can go back and tell them Honda Specifical state NOT to use rtv as it "sets".
The ONLY way to be safe is a complete strip and clean all the oilways with something like a bore cleaning brush with lots of cleaning fluid plus remove the oil jets in the head and super clean them and oilways. I have seen those blocked by a piece of scraped off base gasket never mind silicone

[ekpent]

In the next to last picture of the top of the head, what is that plug looking thing around the oil jet's o-ring? I am seeing your picture correctly?

I was scratching my head a little on that picture also Jerry. Was looking to make sure the o-rings were there but was wondering what the heck that thing was.

[bryanj]

Is it the o ring full of silicone crap?

[Tim2005]

Is it the o ring full of silicone crap?

Yes probably so- though looks like the silicone has been applied to the o-ring. Very odd.  Also I can't work out the black sludge that has accumulated in the low parts of the head. What is that? If it was silicone from the crankcase joint it would have had to go through the oil strainer and the oil filter to get up to there. It doesn't look much like silicone anyway. It can also be seen in the photos from the first rebuild.

[beemerbum]

You can go back and tell them Honda Specifical state NOT to use rtv as it "sets".
The ONLY way to be safe is a complete strip and clean all the oilways with something like a bore cleaning brush with lots of cleaning fluid plus remove the oil jets in the head and super clean them and oilways. I have seen those blocked by a piece of scraped off base gasket never mind silicone

Sue'em. Seriously. If this outfit represented themselves as qualified to work on these decades old motors, they should be liable for damage to your motor. It should be obvious to anyone who assembles a motor that excessive goop on mating surfaces will find its way to the interior of the motor

[Don R]

 The black goo is probably a combo of aluminum dirt and burned up oil.

[Jonm99]

You can go back and tell them Honda Specifical state NOT to use rtv as it "sets".

Thanks, any chance you can send me a screen shot or link to this statement by Honda? This could very well be the difference between the mechanics taking responsibility, or not.

[Jonm99]

The black goo is probably a combo of aluminum dirt and burned up oil.

Makes sense, don't see what else could make it up there. On the other hand, they found some of that goo in the lower part of the engine when they first opened it up (to swap the gear). Could also be two separate issues (when I overhauled the engine, it was everything but the cases / gear, so could be something that's been sitting there for years and unrelated to the gunk that formed at the top from a mix of shavings and burnt oil).

[69cb750]

Thanks, any chance you can send me a screen shot or link to this statement by Honda? This could very well be the difference between the mechanics taking responsibility, or not.

The holes in the oil restrictor jets are small, silicone will block them and destroy the cam shaft and blocks.
The cb750 shop manual tells you what to do, it does not include a list of things not to do.
For example -
Don't use a sledge hammer to install cylinder on pistons.
Don't use a shotgun to clean your points.
Don't rev the engine to 12,000 rpm to seat the rings.
Don't use silicone.
You need a non sillycone "garage".

[Jonm99]

LOL... Fair enough!