DO THE TON

Blood Sweat Tears and Grease => Engines => Topic started by: Joseph New York on May 16, 2017, 18:39:12

Title: Cams not getting oil
Post by: Joseph New York on May 16, 2017, 18:39:12
The 81 CB750 DOHC is at a shop, I told em I needed them to check the valves as I was hearing slight sounds. They had the bike for other reasons I wasn't equipped to fix myself...

Under the valve cover was a melted gasket, a lightly scorerd lobe, and NO OIL.

They ran it with the top off and no oil was coming up. To rule out the pump they went in with a scope and it was operational.

Obviously the thing to do is remove the top end and find out what's going on. Maybe it's the head gasket. Unfortunately they have the bike and I can't afford to pay for a rebuild that costs more than the bike. So we're trying to brainstorm possible reasons the head is dry and hopefully y'all can throw your hat in the ring.

Clogged oil passage is the only thing I can think of. Going to have them go through the filter and pan and see if anything is there, but I can't think of another way to check for a clog without the head removed.

Anyone here have any ideas?

Worst case senerio is I fill up the head manually and ride it to my garage, but they are going to insist I tow it...

Thanks
Title: Re: Cams not getting oil
Post by: datadavid on May 17, 2017, 04:14:56
Fill up the head manually? You know how this works right? Those cams are riding on pressurized oil film straight on the cylinder head alloy. Run it without pressure = its toast.
Title: Re: Cams not getting oil
Post by: cxman on May 17, 2017, 07:19:58
does your oil pressure light work

is it on when you turn the key on and off when you start the bike?

maybe you just dont have any oil pressure
Title: Re: Cams not getting oil
Post by: hillsy on May 17, 2017, 08:49:17
I'm trying to picture how they stuck a scope in there to work out that the oil pump is OK.... ::)
Title: Re: Cams not getting oil
Post by: cxman on May 17, 2017, 09:38:20
me to???
Title: Re: Cams not getting oil
Post by: Joseph New York on May 17, 2017, 12:05:17
"Filling up the head" hah I'm talking about lubing the cams so I can ride up the street. I'm not really serious about that. No shop would let that happen anyway.

"Scoped the pump" I didn't do this myself, but we were checking if the screen came off. No, ya can't tell it's OK with the scope, but we were checking if it's intact. The bike was layed down in traffic, so we thought it wouldn't hurt to look at its physical condition. Oil pressure is the real test...

"Oil pressure" I wish I knew man. She doesn't have any dummy lights or gauges. The pressure is the real test, I'm sure they are looking into it, I didn't want to insult them in asking, although in tomorrow's meeting I will be bring it up if they don't.

Sorry I don't have all the info for y'all to help right now, just looking for ideas I can include in tomorrow's discussion. I'll post back with what they say tomorrow.

Thanks guys
Title: Re: Cams not getting oil
Post by: cxman on May 17, 2017, 18:18:49
this is not rocket science you use a test light and check

or unscrew the sending unit and put a mechanical pressure gauge in and crank it over

and if you are going to a meeting and ask them if they have done a pressure check and they say no

we will look into that

you have your bike at the wrong place ! they should have done that first
Title: Re: Cams not getting oil
Post by: Joseph New York on May 18, 2017, 01:36:01
this is not rocket science you use a test light and check

or unscrew the sending unit and put a mechanical pressure gauge in and crank it over

and if you are going to a meeting and ask them if they have done a pressure check and they say no

we will look into that

you have your bike at the wrong place ! they should have done that first

Hah they won't say that. They checked the pump screen first because it takes two seconds to rule out. I also told em it's always ran fine for years and without oil pressure I'm sure things would have been much worse.

Reguardless, I'm trying to get out of the shop. Hoping I could hear some ideas here of possible causes yall could share.  I'll report back tomorrow after I hear the update.

Thanks all
Title: Re: Cams not getting oil
Post by: cxman on May 18, 2017, 08:39:02
you need to do some checking its going to be a investigation

lack of oil

no oil pressure

a blockage in the oil galleries

if the motor has not been tampered with or anything has changed

it hard to say
Title: Re: Cams not getting oil
Post by: Joseph New York on May 18, 2017, 12:19:04
Yeah man, it's why I'm here grabbing for straws. I don't want to pay for an investigation, I didn't bring it in the shop for engine work, especially at their busiest time.

Let's say it's a blocked passage, is there any way to test for that without pulling the engine? I guess that's my real question I have for you guys. I've been looking at diagrams and the passages look like the catecombs. Pushing air through, somewhere?

In case the head gasket is leaking, I've read that it's possible to re-tighten head bolts. Dunno, it looks like I'll have to have it towed from the shop, find out more in a few hours...
Title: Re: Cams not getting oil
Post by: cxman on May 18, 2017, 16:22:06
i take the side cover off pull the electric sending unit

screw in a mechanical test gauge and start it up and see what the oil pressure is

that should have been step one

i would not think past that till you even see if it has pressure

it may not be pumping oil period
Title: Re: Cams not getting oil
Post by: Joseph New York on May 19, 2017, 16:11:36
The're tell'n me 4-5lbs at idle. Of corse the head wouldn't get oil.

I'm just going to tow her home and rebuild it myself. It has a head gasket leak so it will have to be done anyways.

I'll post back once I find out what's going on in a few weeks, thanks for y'all help.
Title: Re: Cams not getting oil
Post by: esmoojee on May 20, 2017, 10:01:02
Have you cleaned your pick up screen?  It could be blocked and the passage from the screen body is narrow.  There is a mod from a member on the cb1100f.net site that sells modified screens to allow more oil to flow through.  Your oil pipe could be blocked as well.  It delivers the oil from the case to the head.  Itís the s shape pipe on the outside of the case.  Iíd try these first.  Youíll have to drop your pan to inspect the pickup screen but it may be worth it. 
Title: Re: Cams not getting oil
Post by: teazer on May 20, 2017, 11:42:47
What is stock tickover pressure specification?  That sounds really low.

If it's as low as it sounds, teh reasons could be blocked inlet or a spun bearing that's allowing oil to just piss out back into the sump.
Title: Re: Cams not getting oil
Post by: Joseph New York on May 20, 2017, 12:38:55
Have you cleaned your pick up screen?  It could be blocked and the passage from the screen body is narrow.  There is a mod from a member on the cb1100f.net site that sells modified screens to allow more oil to flow through.  Your oil pipe could be blocked as well.  It delivers the oil from the case to the head.  Itís the s shape pipe on the outside of the case.  Iíd try these first.  Youíll have to drop your pan to inspect the pickup screen but it may be worth it.
I haven't. During my rebuild I'm cleaning everything. I'll look into that aftermarket screen, thanks. Without the bike in front of me, I totally forgot about that external pipe, interesting.

What is stock tickover pressure specification?  That sounds really low.

If it's as low as it sounds, teh reasons could be blocked inlet or a spun bearing that's allowing oil to just piss out back into the sump.
Yes, I think that's super-low. All I was told from the shop is it was 5-6 at idle and that's all I needed to know before deciding to take it back from em. Once I get her in my garage, I'm checking oil pressure, reviewing oil pan/filter, running compression and leak down test, then disassembly, remove all carbon, replacing all gaskets, adjust valves, etc. I've never inspected the cause of low oil pressure, any tests or reviews I should preform to find the culprit, before disassembly, and after?

Guys, on a side note, I'm suspecting the shop didn't check the oil pressure (I could be wrong) but during my call with them, we talked about causes of the dry cam. Then I asked about the oil pressure and he said it was very low. If the oil pressure was low, why would we even be discussing why the head wasn't receiving oil?
Title: Re: Cams not getting oil
Post by: cxman on May 20, 2017, 16:39:58
like i said you had the wrong shop

60 psi is about the relief pressure

i would expect around 20 psi hot idle 30-40 cold idle
Title: Re: Cams not getting oil
Post by: esmoojee on May 20, 2017, 19:14:07
From what I read on the cb1100f.net forum you want about 10psi at idle and 80 when riding.  Check your oil pressure relief valve as well.
Title: Re: Cams not getting oil
Post by: Joseph New York on May 21, 2017, 15:12:03
like i said you had the wrong shop

60 psi is about the relief pressure

i would expect around 20 psi hot idle 30-40 cold idle
Once I get it out of there I'll be happy. Wow that high, hu?


From what I read on the cb1100f.net forum you want about 10psi at idle and 80 when riding.  Check your oil pressure relief valve as well.

The shop told me they'd want around 12 idle, I'll find out soon enough what the pressure is and go from there. The fact that the bike has been running for as long as it has with low pressure (so they say), dry cams, and a leaking head and valve cover gasket, is nothing short of a miracle. Y'all wouldn't believe what this bike has been through.

Just ordered gaskets, not sure what else I will be needed, will be my first DOHC motor build. Shim over bucket  :o
Title: Re: Cams not getting oil
Post by: cxman on May 21, 2017, 18:42:32
10 lbs per 1000 rpm hot is a universal minimum for 4 stroke engines till relief pressure limit is reached
Title: Re: Cams not getting oil
Post by: cxman on May 21, 2017, 18:43:53
if its been running with dry cams you are going to need at least another head and cams

the cam runs right on the aluminum head no oil film you have scrap
Title: Re: Cams not getting oil
Post by: Joseph New York on May 21, 2017, 21:20:20
if its been running with dry cams you are going to need at least another head and cams

the cam runs right on the aluminum head no oil film you have scrap

Ok wow I prob should have known that, thanks
Title: Re: Cams not getting oil
Post by: Joseph New York on May 21, 2017, 21:44:37
if its been running with dry cams you are going to need at least another head and cams

the cam runs right on the aluminum head no oil film you have scrap
I went in the shop to inspect this. It's insane, went through every lobe and they all look perfect, one had a dark scar but not even the slightest groove or score. I'm going to go through it again when I get em off.
Title: Re: Cams not getting oil
Post by: datadavid on May 22, 2017, 05:13:16
if its been running with dry cams you are going to need at least another head and cams

the cam runs right on the aluminum head no oil film you have scrap
Glad you mention that as well, i dont think he read it when i mentioned that

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Title: Re: Cams not getting oil
Post by: datadavid on May 22, 2017, 05:13:39
Ok wow I prob should have known that, thanks
Yes i told you last week..😃

Title: Re: Cams not getting oil
Post by: datadavid on May 22, 2017, 05:18:19
I went in the shop to inspect this. It's insane, went through every lobe and they all look perfect, one had a dark scar but not even the slightest groove or score. I'm going to go through it again when I get em off.
Did you remove the cam caps? You need to check the bearing surfaces first. But if no blue lobes and no scored bearing surfaces, then guess what? You have oil pressure up there.
Title: Re: Cams not getting oil
Post by: Joseph New York on May 26, 2017, 00:24:56
Yes i told you last week..😃

Oops I quoted the wrong line here, did it twice. I meant I should have known the equation: 10 lbs per 1000 rpm hot :D
Title: Re: Cams not getting oil
Post by: Joseph New York on May 26, 2017, 00:35:31
Did you remove the cam caps? You need to check the bearing surfaces first. But if no blue lobes and no scored bearing surfaces, then guess what? You have oil pressure up there.

I didn't, in fact I can't say for sure that I got a proper look at everything.

And your right, I'm totally open for the fact that the shop misdiagnosed everything. I rode her hard for a long time with little side effect and little to no wear.

The real test is when I get her home and and take her top off ;)
Title: Re: Cams not getting oil
Post by: crazypj on May 26, 2017, 15:36:18
Pull the sump off and check the pick up isn't blocked.
If motoir has been apart and silicon sealer used, you can almost guarantee it's blocked at least one feed hole. Worst case scenario is the outer rotor of oil pump broken.
Oh, pull oil filter and check the spring and washer are in place (and the pressure release valve in bolt isn't stuck open)
 The engine is about 212lbs, the shape makes it real awkward to move around and get out of frame. Couple of people have used carr engine hoists to lift it (I'm way too old and fragile to try lifting one nowadays  :( )
Title: Re: Cams not getting oil
Post by: Joseph New York on May 27, 2017, 12:22:06
Pull the sump off and check the pick up isn't blocked.
If motoir has been apart and silicon sealer used, you can almost guarantee it's blocked at least one feed hole. Worst case scenario is the outer rotor of oil pump broken.
Oh, pull oil filter and check the spring and washer are in place (and the pressure release valve in bolt isn't stuck open)
 The engine is about 212lbs, the shape makes it real awkward to move around and get out of frame. Couple of people have used carr engine hoists to lift it (I'm way too old and fragile to try lifting one nowadays  :( )

Great, pointers to what I should do when I get the bike back is a help. 212lbs!! I'm young but built like a pencil, I'm not picking it up either. Sounds like a I'll be needing to call in on some favors.

What are some tests I should do while the bike is still in the frame, other than leak-down and compression, preferably in the oil category?

Title: Re: Cams not getting oil
Post by: crazypj on May 27, 2017, 15:32:44
There should be an oil gallery plug screwed into bottom of right side crankcase. you can fit a pressure gauge there and see what pressure you really have.
Title: Re: Cams not getting oil
Post by: Joseph New York on May 29, 2017, 13:35:13
There should be an oil gallery plug screwed into bottom of right side crankcase. you can fit a pressure gauge there and see what pressure you really have.

I wish man, DOHCs don't have accessible oil galley ports like SOHC. I think I'm supposed to build my own L pipe fitted to a gauge and replace the oils pressure switch. I wasn't going to ask how can I get a pressure reading in this thread, but yeah, how do I get the pressure? The only tester I know of is OEM 07506-3000001 mentioned in the manual that but costs $300. Any aftermarket solutions out there?
Title: Re: Cams not getting oil
Post by: crazypj on May 31, 2017, 16:40:13
The shop who told you 4~5 psi probably looked at " A "manual and only saw that's the switch pressure. In my opinion Honda did a real dumb thing and mounted oil pressure switch on outlet side of pump so oil light goes off as soon as engine starts to turn over. (and if oil light comes on when engine is running, it's already too late to do anything)
That's why I said to check at main oil gallery. I would just get a spare gallery plug (or a short bolt that fits) and drill/tap for a banjo fitting, there isn't any need for a $300.00 gauge as a normal cheapy one will work fine (even if not 100% accurate)
The gallery plug is a 'standard' Honda thread so picking on up from crashed/destroyed motor shouldn't be too difficult
 I did buy genuine Honda vacuum gauge set though  - in 1978 it cost almost 3 weeks wages but still works fine today so guess the extra quality was worth it (the 'new' mechanical ones were no better than any aftermarket set  ;D )
Title: Re: Cams not getting oil
Post by: Joseph New York on Jun 01, 2017, 15:35:36
The shop who told you 4~5 psi probably looked at " A "manual and only saw that's the switch pressure. In my opinion Honda did a real dumb thing and mounted oil pressure switch on outlet side of pump so oil light goes off as soon as engine starts to turn over. (and if oil light comes on when engine is running, it's already too late to do anything)
That's why I said to check at main oil gallery. I would just get a spare gallery plug (or a short bolt that fits) and drill/tap for a banjo fitting, there isn't any need for a $300.00 gauge as a normal cheapy one will work fine (even if not 100% accurate)
The gallery plug is a 'standard' Honda thread so picking on up from crashed/destroyed motor shouldn't be too difficult
 I did buy genuine Honda vacuum gauge set though  - in 1978 it cost almost 3 weeks wages but still works fine today so guess the extra quality was worth it (the 'new' mechanical ones were no better than any aftermarket set  ;D )

Cool, so you are suggesting I tap my own oil galley port like the SOHC bikes have and screw in a guage. I could do it, I've seen it done before on an SOHC to to relocate it further in.

Did you say you knew of a cheaper aftermarket guage that I could test the pressure at the switch port?  If so I may start there before tapping it. I can only find OEM NOS.

I was also thinking about tapping into the oil line that feeds up from the case to the valves, externally. Would that be a possible place of getting a reading? Could possibly get put in a T pipe.

Thanks
Title: Re: Cams not getting oil
Post by: cxman on Jun 01, 2017, 20:36:04
this might do it

https://shop.advanceautoparts.com/p/autometer-banjo-bolt-2276/10455285-p?c3ch=PLA&c3nid=10455285-P&iv_=__iv_p_1_a_810678608_g_40371513285_w_aud-296857279645:pla-329229809404_h_9009610_ii__d_c_v__n_g_x_pla_y_6201684_f_online_o_10455285-P_z_US_i_en_j_329229809404_s__vi__&utm_source=ACQ&utm_medium=cpc&utm_campaign=PLA&utm_content=shoppingcampaigns&gclid=COn-ja3nndQCFdY9gQod7OgDbw#fragment-4


http://www.autozone.com/fittings-and-hose-line-connectors/fuel-fitting/russell-m12-x-1-25-banjo-bolt-adapter-fitting-with-1-8-in-npt-female-port-for-use-with-russell-640910-641110-and-641120/773861_0_0
Title: Re: Cams not getting oil
Post by: Joseph New York on Jun 02, 2017, 10:57:03
this might do it

https://shop.advanceautoparts.com/p/autometer-banjo-bolt-2276/10455285-p?c3ch=PLA&c3nid=10455285-P&iv_=__iv_p_1_a_810678608_g_40371513285_w_aud-296857279645:pla-329229809404_h_9009610_ii__d_c_v__n_g_x_pla_y_6201684_f_online_o_10455285-P_z_US_i_en_j_329229809404_s__vi__&utm_source=ACQ&utm_medium=cpc&utm_campaign=PLA&utm_content=shoppingcampaigns&gclid=COn-ja3nndQCFdY9gQod7OgDbw#fragment-4


http://www.autozone.com/fittings-and-hose-line-connectors/fuel-fitting/russell-m12-x-1-25-banjo-bolt-adapter-fitting-with-1-8-in-npt-female-port-for-use-with-russell-640910-641110-and-641120/773861_0_0

Interesting! Thanks for the links.

Would this banjo bolt fit in the oil switch port and provide a the port to use an aftermarket guage, like this: https://www.summitracing.com/parts/pro-67405
Title: Re: Cams not getting oil
Post by: crazypj on Jun 02, 2017, 16:20:47
I think the pressure switch is a 1/8" BSP taper thread?
You should be able to rig something up for less than $50.00. Probably not a good idea to have it permanently fitted, the pressure variations can be frightening (even though it's normal running condition)
I just had to dig out manual as I've been confusing myself with the oil passages. Isn't it possible to remove the gallery plug on top right side then fit a banjo bolt there? (similar to SOHC placement although 'hidden' behind alternator cover)
If you replaced the line with an Aeroquip (or similar) stainless one you could have that Summit gauge permanently mounted.
For $25.00, can't go wrong  8)
Title: Re: Cams not getting oil
Post by: Joseph New York on Jun 09, 2017, 00:33:33
I think the pressure switch is a 1/8" BSP taper thread?
You should be able to rig something up for less than $50.00. Probably not a good idea to have it permanently fitted, the pressure variations can be frightening (even though it's normal running condition)
I just had to dig out manual as I've been confusing myself with the oil passages. Isn't it possible to remove the gallery plug on top right side then fit a banjo bolt there? (similar to SOHC placement although 'hidden' behind alternator cover)
If you replaced the line with an Aeroquip (or similar) stainless one you could have that Summit gauge permanently mounted.
For $25.00, can't go wrong  8)

I didn't know about a galley port other than the oil switch? I'll look into it! It's strange that my manual wants us to check at the switch port..

Hopefully I can use the banjo bolt and guage somewhere, and if I find the port under the alt cover, I'll work on building a permanent one. Thanks
Title: Re: Cams not getting oil
Post by: crazypj on Jun 09, 2017, 15:38:01
I think the plug behind alternator cover is 14mm or 16mm thread with a 14mm head. You must use a 6 point socket or it will round over (way too long since I looked inside to remember)