345 V8 valvetrain noise

S

sean sirvaitis

New member
Ok, so I just bought a 76 traveler with the fiberglass pickup top. 345 v8, manual 4 speed, 4x4, rust free... Sweet. The only problem is that when I looked under the hood I discovered that the previous owner had "prettied up" the engine bay, and routed the plug wires together in a loom set. I corrected the plug wire routing, and immediately the motor went from a v6 to full v8 status... Except now the valves on the #7 cylinder are extremely loud. I was wondering if I needed to have the motor pulled and rebuilt, or if a top-end overhaul would suffice. I know the cross-firing can damage the valves, but I was hoping there might be a valve adjustment I could try before throwing a bunch of $$ at it. Is the 345 equipped with adjustable valves? And if not, does anyone know what a top-end rebuild would cost? I'm still waiting for my parts and service manuals to arrive, so I'm kind of stuck at the moment.

Also, I got a full set of original fiberglass fender flares for the Scout II, anyone know what those would be worth? I'm planning on putting them on the truck, but it would be nice to know if what I paid for them was worth it. I assume of course that they're much better quality than the bushwhacker abs flares, as they're ridiculously sturdy, but I would appreciate any opinions you guys have. Thanks!
 
sean sirvaitis said:
ok, so I just bought a 76 traveler with the fiberglass pickup top. 345 v8, manual 4 speed, 4x4, rust free... Sweet. The only problem is that when I looked under the hood I discovered that the previous owner had "prettied up" the engine bay, and routed the plug wires together in a loom set. I corrected the plug wire routing, and immediately the motor went from a v6 to full v8 status... Except now the valves on the #7 cylinder are extremely loud. I was wondering if I needed to have the motor pulled and rebuilt, or if a top-end overhaul would suffice. I know the cross-firing can damage the valves, but I was hoping there might be a valve adjustment I could try before throwing a bunch of $$ at it. Is the 345 equipped with adjustable valves? And if not, does anyone know what a top-end rebuild would cost? I'm still waiting for my parts and service manuals to arrive, so I'm kind of stuck at the moment.
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The sv engines in light-duty apps were all equipped with hydraulic valve trains as far as I know, so there is no adjustment other than a measured preload on the lifters themselves. A top-end rebuild can be had through this place, just go onto the main page and call up Jeff about his current stock. I can vouch for the fact that this is the best place to buy IH parts, due to the reasonable prices and excellent service handed out through these forums. It would be wise to read through and absorb some of the IH-specific info that is amassed here, if only to educate yourself about your engine. Nobody can make the assessment of "refresh vs. Rebuild" except for you and whoever else witnesses what you find as you work with the motor, though you can get some good advice if you have the time and technology to post pictures.

If this isn't your only mode of transportation, you can always spend money on some gaskets and go about the process of probing into your noise issue with the help of this forum on hand. The service manual will be a priceless tool when it comes to working with this motor, so if you're not in a rush it shouldn't be any big thing to work through this step by step and possibly come out of it all with another IH put into service. I'd say the first step would be snaking out the oil pan to inspect any debris that May have collected, and if you find some big curved grey chunks then we'll know what caused your noise right off. That would be cam bearing failure, basically worst case scenario (since we already know it runs) and there's always the potential that a lack of regular maintenance has just left something clogged, or excess wear has affected tolerances. Obviously we won't know until you start getting dirty!


sean sirvaitis said:
also, I got a full set of original fiberglass fender flares for the Scout II, anyone know what those would be worth? I'm planning on putting them on the truck, but it would be nice to know if what I paid for them was worth it. I assume of course that they're much better quality than the bushwhacker abs flares, as they're ridiculously sturdy, but I would appreciate any opinions you guys have. Thanks!
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I wasn't aware of any fiberglass fender flare options for the Scout II, but if it's true oem then I'd assume they are worth something. Either way, if you're keeping them I'd think value is subjective. The fiberglass sure as hell won't dry-rot like other materials.
 
sean sirvaitis said:
ok, so I just bought a 76 traveler with the fiberglass pickup top. 345 v8, manual 4 speed, 4x4, rust free... Sweet. The only problem is that when I looked under the hood I discovered that the previous owner had "prettied up" the engine bay, and routed the plug wires together in a loom set. I corrected the plug wire routing, and immediately the motor went from a v6 to full v8 status... Except now the valves on the #7 cylinder are extremely loud. I was wondering if I needed to have the motor pulled and rebuilt, or if a top-end overhaul would suffice. I know the cross-firing can damage the valves, but I was hoping there might be a valve adjustment I could try before throwing a bunch of $$ at it. Is the 345 equipped with adjustable valves? And if not, does anyone know what a top-end rebuild would cost? I'm still waiting for my parts and service manuals to arrive, so I'm kind of stuck at the moment.

Also, I got a full set of original fiberglass fender flares for the Scout II, anyone know what those would be worth? I'm planning on putting them on the truck, but it would be nice to know if what I paid for them was worth it. I assume of course that they're much better quality than the bushwhacker abs flares, as they're ridiculously sturdy, but I would appreciate any opinions you guys have. Thanks!
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Sean, welcome to the ihon form. Lot's of good info here you can trust to be right. :yesnod:

here is where I'd start,
pull the suspect valve cover and have a look at the push rods for bending and or a sticky valve. When these IH v8's have valve oiling or sticking issues (common) they like to bend push rods.
Rotate the engine till the offending cylinder is at tdc and check for loose valve lash. If you find a rocker loose between the valve and rocker you should pull the lifter and check for cupping and bad wear.
After inspecting the valve train and find no annomalies see if you can start it and have a look for good oiling to the rockers and the like. It will splash oil around so try to gaurd the bottom edge of the cover rail . Card board works if you can have a helper start it and be ready to shut down if oil gets to messy.
 
If the "loomed" plug cables were an oem "carbon core" type, then inductive crossfire can occur. If they are a modern, helical-wound design, then inductive crossfire is not an issue as the design of the cable material itself acts as a "choke" for this phenomena.

Inductive crossfire can't "damage valves". It can create a detonation issue however which would be audible.

We have posted extensive diagnostics for the very common valve train noise issues regarding these vehicles/engines. Spend a lot of time reading through the extensive threads just in the gas engine tech sub-forum and you will receive an education and get an idea of the diagnostic processes used.

Start here:

http://www.forums.IHPartsAmerica.co...IH-lifter-rattle-syndrome-what-do-I-have.html

And continue to here:

http://www.forums.IHPartsAmerica.co...I-4-sv-engine-non-oiling-rocker-assembly.html
 
Thanks guys. This is the bulletin I was going off of:
 

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sean sirvaitis said:
thanks guys. This is the bulletin I was going off of:
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Yes, that bulletin was pertinent given the oem technology at that point in time. But in the past 35 years much has changed in the engine component and aftermarket world!

Secondary cabling at the point in time when that bulletin (and the assembly line process) was pertinent involved the use of a graphite/carbon matrix (along with either cotton, rayon, or nylon fiber support) for the conductor. That material has an approximate resistance of 2,000+ ohms per foot of length. That was used in order to attentuate rfi (exhibited as crackle or static on the am radios in use at that time) per federal requirements. And that cabling promotes inductive crossfire when an engine has a firing order where two cylinders are adjacent in the firing order and the affected plug cables are run parallel to each other (even when separated by some distance). The simple fix for that condition, simply cross the two cables over each other at some angle less than 180*. That effectively attentuates any possible inductive crossfire.

Instead, ihc chose to route the offending cables well away from each other, and yes, that works also.

Typical carbon/graphite plug cabling has a lifespan of around 10k miles if handled gently and not allowed to run close to an exhaust manifold/heat source. Then the cables were replaced during "major tune-up" which also involved full ignition reconditioning and a carburetor overhaul.

In the 80's, "spiral-wound" or "helical-wound" cabling was introduced in the aftermarket as a "performance upgrade". But in reality it was done because of the vastly increased underhood temps associated with 2nd gen emissions engines. Also...because of the 50k mile federal emissions warranty forced in by the feds, a spark plug cable made of the older material would not last, thereby creating a mis-fire that was exhibited in a failed emissions test. So unless the oem wanted to reimburse for continuous warranty claims under the emissions warranty, the technology had to change...same as the fact that breaker points would not meet the warranty criteria but electronic switches would (usually).

Helical-wound plug cables (both oem and aftermarket) have been the norm for many years, though the performance/aftermarket still pimps the stuff as some high-end innovation. That is pure marketing bs.

The best effect that helical-wound secondary cable has had is...reduction in secondary cable resistance down to the 300ohms per foot range and much better attentuation of rfi with the plethora of electronic devices in use on today's vehicles. The durability of this type cabling is far superior to any old skool secondary cabling, which does still have an application amongst vehicle restoration purists. The secondary effect has been the greatly reduced emf/rfi as some form of plastic has replaced many body panels (the hood) on vehicles which has no shielding benefit in attenuating emf/rfi. This is what allows the use of an ipod jacked into a high end head unit along with a gps-based nav system. Back in my day, we were only concerned with how to reduce the static on our tube-powered johnson cb radios with crystal tuners.

And...the actual technical operation of any modern oem or aftermarket electronic ignition system is based upon the use of matching secondary cabling. Most especially when using an add-on/aftermarket capacitive discharge "box" on these older vehicles.

Up through the 70's, chev fought this issue on the corvette by placing the secondary cables inside of a metallic shield since the plastic hoods/fenders/bodies did nothing for attenuating rfi.
 
Thanks Mike! I'm going to assume the cables are an earlier design, based on the fact that altering the routing did bring two cylinders back to life. Will be installing a new set of modern plug wires this afternoon.


Edit: found two different diameter plug wires... Previous owner was an idjiot.
 
sean sirvaitis said:
edit: found two different diameter plug wires... Previous owner was an idjiot.
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Or just really cheap...

Did you put new spark plugs in? Do not think you mentioned it in your first post...

I would not be surprised if you found a "mix and match" with the spark plugs, also...
 
sean sirvaitis said:
thanks Mike! I'm going to assume the cables are an earlier design, based on the fact that altering the routing did bring two cylinders back to life. Will be installing a new set of modern plug wires this afternoon.


Edit: found two different diameter plug wires... Previous owner was an idjiot.
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I really think that when you messed with the plug cables originally, ya had some poor connections and most likely one or two of the cables (if the oem carbon-type conductor) are actually broken internally. If ya put that engine onna scope (engine analyzer), you would see the failed plug cables instantly.

Rule of thumb for carbon-core secondary cables, the total resistance should not exceed 3,000ohms per foot of length measured including the terminations at each end.

The coil wire is the sane material, same test specs, it's just shorter (usually).

The actual od of the modern cables really has nothing to do with this. The insulation/jacket od (whether 6.5mm, 7mm, 7.5mm, 8mm, 8.5mm) is in reference to the dual (sometimes triple) layer insulation/jacket matrix. The conductor cross/section is the same.

For those that want to retain the appearance diameter of the older oem cables, modern helical-wound stuff is also available, just has a smaller od insulation jacket.
 
Ok. I changed out the oil filter, ran some seafoam through the oil system, and gingerly drove it around for about an hour. The valve noise is gone!! So as you so helpfully pointed out Mike (on another thread), it was probably a lubrication issue. In any event, my emerald green and white rig is purring beautifully at idle, and roarin' at wot, with no more ticking! Thank you all sooo much for your help and suggestions!! I was ready to start pulling my teeth out to numb the pain of paying for a rebuild!!


Edit: thank you also for the detailed rundown of the plug wire makeup.. I'm glad I went with the "midrange" wires instead of the performance ones... You saved me $22!!! (and of course, hundreds on an unnecessary rebuild!)
 
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I remember seeing a really nice green/white terra pick up for sale at a car lot in redmond a couple years ago. Wonder if it's the same one? Glad to hear it's in good hands.
Good luck, Scout on.
 
Interestingly enough, it is the same one! I saw it up for sale back in summer of 2008, when I was working at the chevron station across the street. I bought it last week when I found out it was still available. (amazing that no one scooped it up before I did, but I swear I heard it say it was my truck the first time I saw it) I know.. I know....:out: but how else do you explain no one even putting in an offer?? Im telling ya, it had a cloaking device on it or something!
 
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