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Re: Ignition problems- 305E V6
Jimmy66 #1399026 Fri Feb 26 2021 08:15 PM
Joined: Jul 2018
Posts: 110
X
'Bolter
Old engine with solid lifters being driven shortly after getting it started without running it back in without revving it and checking for proper lubrication after years of sitting is never a good idea. If you are lucky, you will be able to get away with just new pushrods (to replace the bent ones), lifters, maybe a few rocker arms, maybe a cam, possibly a replaced valve or two and a timing chain. the lifters in the block could be stuck, the valves in the head could be stuck and bent. Unlike hydraulic lifters, solid lifters are unfogiving. Any of those components jamming will cause and old timing chain to jump time.

Last edited by Xena; Fri Feb 26 2021 08:25 PM.


Re: Ignition problems- 305E V6
Justhorsenround #1399033 Fri Feb 26 2021 08:35 PM
Joined: Sep 2011
Posts: 856
B
'Bolter
Originally Posted by Justhorsenround
it might be worth a few bucks to get some professional help. I would be wary of one that doesn’t have grey hair.

I look at it for free if it was local. Got all the qualifications!


BC
1960 Chevy C10 driver 235 T5 3.73 dana 44
1949 GMC 250 project in waiting
1960 C60 pasture art
G.M dealer tech since 1980 & counting
Re: Ignition problems- 305E V6
Jimmy66 #1399036 Fri Feb 26 2021 08:53 PM
Joined: Jul 2018
Posts: 110
X
'Bolter
FYI: I worked for Chevrolet as a dealership flat rate mechanic for 25 years rebuilding engines, and I am 66 years old and don't have grey hair.

Last edited by Xena; Fri Feb 26 2021 08:53 PM.


Re: Ignition problems- 305E V6
Jimmy66 #1399038 Fri Feb 26 2021 09:17 PM
Joined: Mar 2020
Posts: 195
T
Shop Shark
Not sure if it will apply to this particular motor, but if you're trying to get a look inside without tearing things down to far I have had success renting a flexible inspection scope. Some have a light built in and some don't, if you don't have a light on the end of it it makes things harder (trying to juggle and aim a really bright flashlight down the spark plug hole is no fun). I would think that if it were a head gasket there would be some oil dribble from the head or heads, unless the motor was super dry on the top end (or already covered in oil to the point where you can't tell if it is leaking). using a flexible inspection scope and very slowly turning the motor by hand (if it still spins) should help to get an idea of what's going on. It helped me find a broken rod on a dormant Benz motor years ago, was better to find it that way than to try to start up without knowing.


62' GMC Fleetside 3/4 ton 235 4-speed.
Time makes fools of us all.
Re: Ignition problems- 305E V6
Xena #1399047 Fri Feb 26 2021 10:26 PM
Joined: Sep 2011
Posts: 856
B
'Bolter
Originally Posted by Xena
FYI: I worked for Chevrolet as a dealership flat rate mechanic for 25 years rebuilding engines, and I am 66 years old and don't have grey hair.

Doing better than me, been with G.M dealers since 1980, I'm 61.5 & have lot of grey hair, happy to have hair!


BC
1960 Chevy C10 driver 235 T5 3.73 dana 44
1949 GMC 250 project in waiting
1960 C60 pasture art
G.M dealer tech since 1980 & counting
Re: Ignition problems- 305E V6
Jimmy66 #1399048 Fri Feb 26 2021 11:00 PM
Joined: May 2005
Posts: 8,017
B
Sir Searchalot
Here is the problem in my little mind. Don't want to recommend tear down of timing chain. Don't want to recommend taking heads off. Don't want to go after the wrong thing.
Keeping in mind that ALL cylinders are low:

1. If it was head gasket, it's a V6, it has two head gaskets. Both blown?
2. If it's timing chain/gear, why did rotor return to point right at no. 1 after rotating motor 360 several times? That seems to indicate no slippage and at least no. 1 would have compression.
3. I don't know if this motor is an interference motor or not. If not, there are no bent valves.
4. I guess if all pistons/rings were stuck or cylinders washed dry, that would be no compression and I guess not even one cylinder would fire?
5. It does have spark, it does have gas, if the test were done correctly by poster.
6. A leak down would be good to do.
7. He does have a scope. All you could see is piston top and walls. I hope they are going up and down. A straw in each hole will tell you that.
8. The 1, 3, 5 bank is not a whole lot different than the 2, 4, 6 bank.

Going to add two good squirts of oil into each cylinder and see what that does for compression. Trying to be sure with limited tools and limited experience and over the internet, before recommending DIY tear down or mechanic services. If a miracle happens and cylinders come up to 125, that will be nice. If not my guess has to be the Martin opinion......timing chain. Should not be that with 60,000 miles. Double roller chain very strong, No stretch in 60K miles. Big strong forged steel gears, But............ the bad thing is I know I'm wrong somewhere.
Going to also repeat the rotor test again now that motor has been cranked a lot. Bring no.1 up to TDC on compression, look at pointer, look at rotor pointing at No. 1 . Then rotate motor 360 and look at pointer and rotor again.


Watch out for careful drivers!!!
I'm away on an ego trip. Will be back on Feb 30.
I'm not an Auto Mechanic, but I play one on TV.
I charge $0.02 for every opinion and I take Paypal.
Plan B is always better than plan A, by definition.
You can't teach a new dog old tricks.


Re: Ignition problems- 305E V6
Jimmy66 #1399060 Sat Feb 27 2021 12:34 AM
Joined: Mar 2019
Posts: 1,232
G
'Bolter
Pull da cap. Look at da rotor. Turn crank in 1 direction till rotor turns. Then turn in da crank in other direction and sèe how far, or degrees it takes to turn rotor. That will at least tell ya if da timing chain is a sloppy mess. Stretched, gear stripped, or other timing issue? Im not convinced that #1 compression stroke is being verified and-or rotor is pointing at #1 when it supposed to. Theres no way this truck went from good running to inoperable in a flash w/o a mechanical failure if all other necessary components are in place.... Fuel, Spark, ..... the other 2 are Timing and Compression that seem to be questionable?? Unless of course da cylinders are washed down?? Then oil squirting will verify that. Unfortunately like previously stated, maybe da kid needs a better hands on, knowledgeable helper? JMO

Re: Ignition problems- 305E V6
Jimmy66 #1399081 Sat Feb 27 2021 03:11 AM
Joined: May 2005
Posts: 8,017
B
Sir Searchalot
He's not a kid. He's 49. Got confirmation pictures of the pointer and rotor.


Watch out for careful drivers!!!
I'm away on an ego trip. Will be back on Feb 30.
I'm not an Auto Mechanic, but I play one on TV.
I charge $0.02 for every opinion and I take Paypal.
Plan B is always better than plan A, by definition.
You can't teach a new dog old tricks.


Re: Ignition problems- 305E V6
Jimmy66 #1399092 Sat Feb 27 2021 05:52 AM
Joined: Jul 2018
Posts: 110
X
'Bolter
So I have reread through the entire 14 pages of this thread and am impressed at the effort made by Bartamos in particular and others in trying to solve Jimmys issue. One thing that I missed on the first read was the latest compression test results. Cylinder #6 had a reading of 70 and then 0 during a subsequent test. I don't recall any mention about oil pressure PSI or the removal of the valve covers to see if the top end (much less the rest of the engine)is being properly lubricated. A reading of 70 PSI and then 0 would indicate to me that a component is sticking for a low reading of 70, or a reading of 0 indicating (to me at least) either a stuck lifter in the block bore or inadequate lubrication of the rocker shaft (which would affect the travel of all the rocker arms), or both, resulting in at least some if not all,valves not closing or opening effectively causing low compression readings. I would also suspect possible cam lobe damage as well. To state the obvious, head gaskets and timing chains are not going to momentarily repair themselves and then fail. Also, metal components, as we all know, expand when they heat up and contract when they cool.

I am more convinced than ever, based on what I have read, that the issue is lubricant related. If it were my engine, I would first remove the valve covers and assess how much fresh oil is visible on the rocker arm shaft, rocker arms and head in general ( it will also provide a good general assessment of the lubrication of the engine parts not visible). If lubrication is fresh and obviously sufficient, I would then assess the condition of the pushrods (at piston TDC you should be able to spin them with your fingers); if they look to be unbent I would proceed to turn the engine over BY HAND (wrench on crankshaft) and assess the rocker arm and valve travel. If all rockers and valves seem to be moving freely, I would then adjust all the valves, one cylinder at a time, and then do another compression test. Compression test readings are always going to be low if the engine has not been warmed up; as in this situation that is not possible, look for consistently close readings between cylinders (10 to 20 PSI would be optimal). Using a oil can to spray oil into the cylinder top and wall gap with oil before testing will temporarily help seal the ring / bore gap and raise the PSI reading. Two adjacent cylinders having a low reading in contrast to normal readings in the other cylinders often indicates a 1 blown head gasket, 2 a cracked cylinder wall between the cylinders, and 3 a cracked head; all three are most often a result of overheating the engine.

Having done all that and everything looks good, I would imagine it would come back around to timing and ignition settings. Below I have provided some valve and ignition info that hopefully will help get it going, from the Service trade Edition of Motor Truck and Diesel Repair Manual 28th Edition:

1966 GM 305-E V-6 engine:
Spark Plug 45ns Plug GAP .035
Distributor Point Gap .019 Timing Mark 5 degrees Firing Order 1-6-5-4-3-2
Valve Lash Intake .012 HOT Exhaust .018 HOT ( Cold, I would look for intake .015 to .017 and exhaust .021 to .024 and plan on readjusting them once the engine is running and hot ). Valve spring pressure (LBS @ inch length) 200 @1 1/2
Compression Pressure at cranking Speed 135 PSI

Valve Adjustment Procedure (verbatim from manual): With engine at operating temperature and rocker arm covers removed, turn adjusting nut on each rocker arm until proper clearance is obtained between valve stem and rocker arm.
Best of luck

Last edited by Xena; Sat Feb 27 2021 06:11 AM.


Re: Ignition problems- 305E V6
Jimmy66 #1399147 Sat Feb 27 2021 06:58 PM
Joined: Mar 2020
Posts: 195
T
Shop Shark
with 4&6 reading so low I would hope for a head gasket or a cracked head on that side, maybe even some head warping from excessive heat. I had seen it happen a bit out here where it gets so hot. occasionally improper torquing of the head bolts could lead to something like that, though this looks worse that any case of that happening that I've seen before. another wet compression test with fairly consistent results may help pin it down.


62' GMC Fleetside 3/4 ton 235 4-speed.
Time makes fools of us all.
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