WolfMann

Thommo if it was a centrifugal spring, how would that issue clear itself up? It doesn't seem like the kind of thing that would be intermittent.

WolfMann

Id like to re-ask a couple earlier questions:

Should I go with a mechanical or digital oil pressure gauge? Can anyone recommend a good one? What kind of plumbing would I need?

What's a recommended way to clean oil passages with engine in truck? Would any sludge/gasket material/etc eventually wind up in the sump?

I'd like to confirm that the timing chain tensioner works on oil pressure, more pressure, more tension, is this the case?

I've read that an old oil pump will cause a loss of pressure, also read that the relief spring can become gunked up and affect pressure that way. Is this true? If so is it possible to clean with pump still in truck?

Thanks again guys.

L5wolvesf

On the possible vac leak I'm not suggesting any part - just anything that operates off of vac. Since you have now eliminated the hoses how about the various plastic pieces they connect to? They are over 30 years old and operate in a hot environment - heat makes plastic brittle. I read here where a guy had broken the hose barb on one of the manifold vac sensors.

Once you have the stethoscope you'll be able to track down the noise - that should give you a better direction to go in.

L5wolvesf

I’m going to presume you meant mechanical or electrical – referring to the operation of the sending unit. Electrical is more in line with what the manufacturer has in the truck. So you may be able to use the existing sensor wire. I use Autometer in all my vehicles (street or race), VDO and Stewart Warner are good too.


So can worn engine bearings – how many miles on the engine? Has it been maintained well or not so?

Thommo Thompson

worn engine bearings are more responsible for pressure loss than a worn pump. usually.
a pump provides the flow, the restrictions create the pressure. however if the flow is limited, the pressure drops, however flow really isnt limited until a pump is so worn it hardly flows at all. In short, a pump failure is highly unlikely but does happen.
as for pressure relief valve, it is just that, it is not a regulator. it only plays a role at the maximum allowed pressure, and does not play a role at any other pressure. it only comes into the equation when oil is cold and thick.
back to my dizzy spring suggestion, if just one spring breaks it coukd be quite tempremental, as the second spring would be working. its just the only simple failure i can think of that would cause a noise.
also, timing issues are often perceived as intermittent, as different situations, "hot vs cold, low vs high rpm, low vs high manifold pressure etc", all affect how well the flame ignites at a given timing. i would be chexking the distrubtors insides before going to tge extents of other areas, as the issue seems to be all related to..... timing.

Thommo Thompson

but to be sure im on the same page as u, u habe a timing issue right? timing is co trolled by the dizzy, and ur not wanting to check that first? i really strongly suggest u check that first. that is its sole job.

Old83@pincher

First... if its a timing issue check out all the guts of the distributor. Make sure the advance plate and its bearing all move smoothly with little resistance. You can quick check that buy simply turning the rotor and seeing if it moves smooth and returns. Make sure the mechanical advance and its weights all move smooth too... I had that problem...took the distributor apart and re-built it.
Second...ditch the Fram filter and use the dealer one...they're cheaper, at least here in Taxtario then the Frams, I also notice way quicker oil pressure build up on cold starts.

Its un-likely the timing issue is caused by the tensioner as the chain is always tight on the right hand side and rotation is clockwise (looking at the front of the engine). A loose chain is just going to make a lot of noise slapping off the cover and other spots. A stretched chain will cause timing issues or if it jumps a tooth...but it would really run crappy.

However just to entertain it...did you replace the hydraulic tensioner when you did the chain? Sometimes the "discount" brands don't give enough chain tension at idle...I suspect its a weaker spring in them then the factory one. That spring does give a bit of tension particularly at idle before oil pressure builds. Generally this is not noticeable cold but more so when hot. Yes oil pressure pushes the plunger out and tensions the chain during running, it doesn't take that much to do it and not much force is generated even by 65PSI, about where the relief opens (Force = Area x Pressure)

Did you change the oil pump? Maybe you said that? If not its not a big deal to change and may be a quick relatively cheap fix. If the relief valve gets funky, either though wear or dirt jammed in it that could do it. The bargain ones do have some issues so beware.

Any dirt/ old gasket in the oil passages from doing your timing chain should end up in the filter , but maybe not. Beyond the filter is going to the bearings, any crap under the timing cover is going into the sump. But you were real careful and cleaned everything spotless before re-assembly...right?

Gauges...I replaced mine with a Stewart Warner (electrical). You'll need to replace the sender. The thread is NPT on the sender and the thread in the block is BTPT(British Taper Pipe Thread) which is all but identical to JIS. You'll need an adapter. I've heard some people just force it in with mixed results

WolfMann

Thank you all for the useful information, here's an update:
I pulled apart the distributor the other day and it looks like one of the vacuum advance diaphragms has ruptured (would not hold vacuum) I'm thinking this is where the wandering timing comes from. (Good call Thommo) It will advance timing when I give it gas but does not change timing at idle. I believe it's trying to but because of rupture it creates the appearance of the timing mark jumping up a few degrees then falling back. I can't think of a way to repair it (anyone?) So it looks like I'll have to replace that.

Still not sure this explains the noise (could lend to it) but I'm waiting for the stethoscope to arrive. Hoping once I have that I can pinpoint it. I'm wondering if it's maybe from water or fuel pump.

I imagine improper idle timing would have some effect on oil pressure right? Thinking I should hold off on that front until I can address the vacuum advance. Can anyone recommend a place to find replacement? Thought I saw one at lce but it seemed pricey.

dropzone

iTrader: (6)

so have you checked your valve clearance? 22r's will sound like a sewing machine about to implode if the valves are off

WolfMann

Valves were good last time I checked, might go over them again, been doing a lot of double checking lately.

Thommo Thompson

damn, well a ruptured diaphragm isnt repairable. ive seen some adjustable replacement advance mechanisms online but no idea if u could get them to suit a 22r. does this have two diapbragms? if so, one is for manifold vac and the other is for ported. if it only gives advance while running but not at idle, then the one which is currently connected to manifold is stuffed. in which case, u could get away with swapping the hoses, and better still, just capping the ported hose and running solely off manifold vacuum.
understand?
so use only one of the two advance diaphragms but run it off constant manifold vacuum.
this will have a two factor positive effect. it will a. return timing closer to std at idle, and b, will fix the vacuum leak that the ruptured diaphragm presented.

WolfMann

I hear what your saying Thommo. Yeah vac advance has two diaphragms. Just to make sure I understand, I want timing advance under acceleration, and to cap off the other ports for idle advance on diaphragm and hard line. Is that right?
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Thommo Thompson

well no, vacuum advance is designed to advance the timing under low load and let it go back to low advance under high load (when there is lots of fuel so it burns faster). these twin diaphragm systems are a bit strange, in that they use both manifold vacuum and ported vacuum at once. at idle, it takes full manifold vacuum and advances timing to get the fire started early to completely ignite the smaller amount of mixture.
then when u crack the throttle the ported vacuum is then (only if engine is over a certain temp) supposed to supply even more vacuum to the Second diaphragm. this carby "ported" line is the one i would plug. then attach the line from the manifold vacuum port to the good functioning diaphragm.
the manifold one is allways the first to go bad because it gets lots of oil spray in it. im still not sure exactly how this happens, but it does get oil simply because the manifold gets lots of oil flying around in it from the pcv system. that oil attacks the rubber over time.

so in short.
u actually only really want timing advance under low load, like idle and cruise. with both lines connected, the manifold vacuum signal would drop significantly as u press the accelerator, but the extra vacuum from the carby port would add a little bit more vacuum just to smoothen it off. but this ported vacuum suction is very small, and was therefor connected to the part of the diaphragm with the bigger chamber and that gave the weak signal more effect (mrchanical advantage). so now u will be overpowering that larger diaphragm with a very strong manifold vac signal, and this will overcome the fact that there is one less vacuum source.
the reuslt is that it will idle with a higher advance (and probably idle much smoother) butvtaper off more rapidly under acceleration to keep deto ation(pingi ) to a minimum.

Thommo Thompson

orry i got part of that mixed up. the vsv woukd actually turn on and off the "manifold vacuum" when temperature required it, not the "ported vacuum"

WolfMann

So if I'm hearing right, there's manifold vacuum and ported vacuum, the manifold is for idle advance and ported is for timing advance under acceleration. I went out and fiddled with the lines, I plugged the bad diaphragm and then switched the good line between ports (plugging the one not being used) one port advanced timing way past 12° under acceleration, so this is the ported vacuum line? The other line would advance timing about 3° under acceleration, so this is manifold vacuum? And your saying I want the good diaphragm hooked up to manifold vacuum?
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WolfMann

Quick post to answer a few questions and ask a couple more.

I used an engnbldr timing chain kit when I replaced it, this has to have less than 1000 miles on it. Seems everyone recommends engnbldr, I figured it was fairly high quality.

Anytime I've taken things apart I've tried to be mindful of gasket/mess. That's not to say I didn't overlook something, but I don't think I've been sloppy with it.

P.O. Told me engine was rebuilt with about 50,000 miles on it, odometer wasn't working when I bought it, so 50,000 is hard to confirm. He did provide paperwork from the shop that did the rebuild, it seemed kosher to me.

The timing plays a role in this, but I'm more confused by the correlation with the noise in front. Timing mark will wander between 5 and 8 with the rattle noise, when the noise goes away timing is steady and usually close to 0.

I can hear the pit-pat of the valves under the rattle noise while it's happening so I'm inclined to rule that out, and if it was a burnt valve, would that present intermittent symptoms? I'd assume it would be constant.

I'm also inclined to rule out fuel pump and water pump, I don't think they would have that kind of impact on timing, right?

The last time it cleared up in town I made a point of listening up and down the engine, no crank/bearing noise (again would that be an intermittent thing if it was an issue?) Nothing noticeable from exhaust, soft patter of valves, and steady drum of air intake. No noise from the front.

I did take Thommo's advice and plugged the faulty advance diaphragm, experimented with attaching good diaphragm to both port and manifold lines and still had the timing mark jumping around (rattle noise was present), so while I acknowledge theres an issue with the vac advance diaphragm I don't think it's causing this noise or is the heart of the problem.
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I'd also like to mention again that after a longer trip (town and back) the oil light will start to come on the dash. It turns off as soon as I give it gas, and won't come on during small drives around the property.

Thommo Thompson

hmmm
yeh leta get back to that rattling issue coz thats ur biggest concern i guess. the fact ur seeing an oil light occasionally is concerning.
the intermittent nature actually doea sound like a stuffed oil pressure relief valve, perhaps its been damaged by debris. it is before the filter so damage can be made. especially seeings as u say that the motor was rebuilt.
low oil pressure would indeed induce piston slap. that would sound more like someone clapping their hands.
i now womser, being 1983. perhaps u have a single row chain, they came in about 1983. they cause a problem because they expand beyond the capability of the tensioner and must be replaced quite often.
can u confirm which chain u have. it may simply be that.

Thommo Thompson

ahh sorry u said it has a new chain.
does that mean we can rule it out?
maybe..
it might be time to get the sump off and check out the oil pump and Relief valve.
as for checkin oil preasure, get a mechanical gauge (u can rely on them more) and screw it into the pressure sensor port which i think is near the oil filter. get the car hot and run the car at idle and see what the pressure is when this noise is happening. u might find its fluctuating. if it is, the pump may be stuffed.
if its low, the relief valve may be damaged.
does this happen less when the engine is cold?

Thommo Thompson

sorry i have to bring this back, i dont want to leave u with the wrong idea of hoq it works.
under acceleration, (foot down increasing speed) the mixture is strong and u want little to no advance.
the ported advance is aimply located just above (before) tge throttle plate so that it only gets vacuum when the throttle is slightly opened. this was an emmisions related thing back in the day. it allowed the engine to burn off more hydrocarbons in the exhaust by keeping the timing static at idle, and not letting it get vacuum till the throttle was pressed. the idea was u disnt need power at idle, only when u physically demanded it. then things got more advanced and we ended up with the 2 systems running in parralel, like this toyota setup.
adding the extra advance from the manifold to keep the timing up a little bit at idle so that it ran smooth, plus the extra amount from the ported vacuum as soon as the accelerator is pressed and the throttle plate allows engine vacuum to act on the port.
so i say all this, because i dont want u ending up thinkinh advance is good under acceleration. its not, its the opposite.
vacuum advance is for low load.
centrifugal advance on the other hand (the weights in the dizzy) is for rpm related advance, where the increase in the flow of gasses through the engine causes the need for the fire to start earlier. (all about dynamic vs static pressure) ignoring popular incorrect belief, it has nothing to do with how fast the piston is moving up the chamber.

so to recap, for a given engine speed, or a given road gradient, the harder u push the accelerator, the more retarded the timing. ie, u push accelerator, and the diaphragm relaxes and lets timing back closer to 0.

it is for this reason u must set timing with advance lines unplugged.

L5wolvesf

Just a thought re the noise. I guess I missed that you had a new T/c already. A rattle started up earlier this year on my 84 - it was the A/c idler pulley. I removed the belt and pulley since my A/c is disconnected. Another possibility is the alternator.