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hazards related to no start?? *Cam shaft pin

conehead

Member
Joined
Apr 21, 2021
EDIT*
1) A 13/64th drill bit is almost the perfect size for a cam shaft locater pin. Little bit of sanding down gets it right down to the ~5mm that it needs to be (the piece I extracted measured 5.02, and the bit I used was 5.11)

2) Always make sure you at top dead center before assuming your timing is correct, and do check that cam locater pin.
3)the rest of this post is basically just me jabbering


1994 940 Turbo
Stock LH/EZK
ebay turbo, brown top injectors from a thunderbird?
Ran pretty well besides a leaky blow off valve.

Another no start thread, and Id like to start off by thanking ZVOLV, for that amazing no start thread.


Sorry for the wordiness but I feel i have to lay things out exactly as it happened.
I tried to turn on my hazards yesterday on my way home from work, nothing crazy just a stopped vehicle in front of me, around a blind turn and I knew there was a big dump truck bringing up the rear. Hazards didnt come on, and I started hearing a relay buzz. Eh, whatever. Go to make the next turn however, and I realize my blinkers arent working. Some more fiddling with the hazard switch, which I had left in the on position, got the hazards to work normally, and after turning them off, the blinkers were fine. About a mile later, I'm going down a long hill and hit the overdrive button to go to 3rd. When I do this in this vehicle, I often give the gas a little brap brap, to pretend like I'm rev matching my crappy auto trans, but anyway, point is when I gave it the tap tap, nary a brap brap was had, and I realized the engine was either shutting off or potentially off already. I coasted to a nice, slow and steady stop into a perfect parking spot at the bottom of the hill. First things first, I put the car in park and tried to start. Cranking away but not even a pop or bang. I got out and started checking everything I know to check,

-Found that the positive terminal was a little bit loose. tightened up, but no change
-3 blown fuses, all 15 amp and all to do with brake lights/shift lock etc. Replaced all and they havent blown again, yet
-Fuel pumps-I can hear the inline pump coming on as it should
-fuel pressure-checked and right around what i think spec is (~40psi)
-ignition coil-check
-Cps checked, found to be slightly chaffed, and swapped with a new one I had laying around, still no change
-spark-I have spark-will recheck all 4 cylinders tomorrow, but i am confident that I have spark
-I sprayed some brakleen in the intake but didnt get any response. Perhaps I should pull plugs, clean out cylinders and try again, also rechecking all four spark plugs
-Injectors firing? still not sure, but i smell gas and tried the injection diagnostic test with the little diagnostic unit and pretty sure I had success (a series of ticking noises)
-I noticed a vacuum port on the manifold had lost the vacuum cap, capped it off again and still nothing. as expected at this point
-Tried a spare power stage or whatever its called, no change, didnt have my voltmeter on me to check either of them for real
-resistor pack looks ok, connectors seem clean
-checked an cleaned fuel rail grounds for good measure, though the pumps shouldnt come on if those were the issue
At this point I towed the car home the last few miles and after arriving checked:
-timing, everything matched up.
-another shot of brakleen, a bigger shot, still nothing!

Im starting to run out of ideas here and Im wondering if the situation with the hazards somehow has a foot in all this. My assumption would be no, and that it was a funny coincidence, just the way me breaking down right outside a mechanics shop who specializes in old swedish cars is a coincidence, but then again Ive experienced a volvo that would shut right off when the brights were turned on....so to me that means the hazards and the associated wiring that they are tied into could be in play.

The car has always had an electrical issue with the dashboard. Speedo doesnt work, backlighting doesnt work and the gas gauge has a mind of its own. The blinker lights are often half lit... and I have not done the car any favors by wiring in a switch for the E fan, as well as a light bar. Cant imagine why those things would cause a no start though.

As of now, I havent heard the car even try to fire up, just keeps cranking away.
 
Last edited:

apachechef

Burnt Sierra Madre
Joined
Jan 26, 2009
Location
An obscure body in the SK system
spark-I have spark-will recheck all 4 cylinders tomorrow, but i am confident that I have spark

how? did you pull a plug?

a slipped or broken timing belt is possible cause.
check for cam movement during cranking under the 710 cap
 

conehead

Member
Joined
Apr 21, 2021
spark-I have spark-will recheck all 4 cylinders tomorrow, but i am confident that I have spark

how? did you pull a plug?

a slipped or broken timing belt is possible cause.
check for cam movement during cranking under the 710 cap
indeed. I dont have a timing cover so i know the belt is good, and I pulled the crank pulley off and verified that timing is correct. It looked like it was a couple teeth off but it was hard to tell with the pulley in the way. Ill hopefully have time tomorrow to pull all 4 plugs and ideally do a compression test soon
 

ZVOLV

<Master Tech>
Joined
Nov 19, 2002
Location
California
I appreciate the "Thank You".

For the hazards, I suspect a bad ground. Just a guess. You need a wiring diagram.

I would be poking around with a test lamp.

Here is a simple start: use a incandescent test lamp.

Power to the injectors?

Power to the MAF?

Power to the coil?
 

conehead

Member
Joined
Apr 21, 2021
I appreciate the "Thank You".

For the hazards, I suspect a bad ground. Just a guess. You need a wiring diagram.

I would be poking around with a test lamp.

Here is a simple start: use a incandescent test lamp.

Power to the injectors?

Power to the MAF?

Power to the coil?
Power to injectors, check.
Power to coil, check.
Power to MAF, not check, will do now. Would no power to the MAF cause a no start though? I would've thought just poor running. Either way, will check.
 

ZVOLV

<Master Tech>
Joined
Nov 19, 2002
Location
California
Which tool are you using to measure power?

Got spark at all 4 plugs?

Got injector pulse? Put a the tip of a screwdriver to the injector and the handle to your ear. Crank. Click click?

Clear flood. Then two longs blasts starting fluid. Start? Keep it running on bursts?

Timing belt jumped?
 

bobxyz

Board Member
Joined
Aug 29, 2014
Location
Boulder CO
For the factory greenbook wiring diagrams, do a google for: volvo TP3904202
and the 1st link at procarmanuals.com seems to work to view and download the manual with minimal hassle.

I'd guess that your hazard switch hadn't been used in ages and was a little crusty. After cycling it a few (or bunch?) of times, it cleaned up the contacts and started working again.

Next guess is that poping out of overdrive on a downhill rev'd up the engine and jumped (or damaged) some teeth on the timing belt. Inspect the belt carefully, make sure it's aligned correctly, and adjust the tensioner (i.e. loosen & tighten the bolt when at TDC).
 

conehead

Member
Joined
Apr 21, 2021
Which tool are you using to measure power?

Got spark at all 4 plugs?

Got injector pulse? Put a the tip of a screwdriver to the injector and the handle to your ear. Crank. Click click?

Clear flood. Then two longs blasts starting fluid. Start? Keep it running on bursts?

Timing belt jumped?

Timing belt is good, took off the crank pulley to get a better look, since I don't have a timing cover. Used the string method. Everything lined up.

I used a test light to verify power to injectors, but have not tried the screwdriver to the ear. I actually just got a stethoscope so that's convenient. I did use the diagnostic unit to test injectors and was able to hear them ticking, which I assumed means they should be coming on when they're supposed to as well, but maybe not?

Tried the clear flood method, pulled plugs and injectors, cranked and let sit while recharging battery, cranked a few more times for good luck, spray spray, crank (fresh plugs in, injectors still unplugged), still nothing.

I admit I still have only checked the two spark plugs, but did throw a new distributor and rotor on.

When I crank the engine over by hand, a slight metallic thunk can be heard ever so slightly, but doesn't continue to thunk when rotating the engine, meaning if I stop rotating, and suddenly start again, I don't hear it. Only makes it after I've cranked it with the starter. Can't tell if it's in the starter area, engine or maybe it's the trans....is this a normal thing I've just never noticed before? Torque converter maybe?

Been digging out the septic all weekend and haven't had much time to dig in with the volt meter.
 

conehead

Member
Joined
Apr 21, 2021
For the factory greenbook wiring diagrams, do a google for: volvo TP3904202
and the 1st link at procarmanuals.com seems to work to view and download the manual with minimal hassle.

I'd guess that your hazard switch hadn't been used in ages and was a little crusty. After cycling it a few (or bunch?) of times, it cleaned up the contacts and started working again.

Next guess is that poping out of overdrive on a downhill rev'd up the engine and jumped (or damaged) some teeth on the timing belt. Inspect the belt carefully, make sure it's aligned correctly, and adjust the tensioner (i.e. loosen & tighten the bolt when at TDC).
Belt is good, my first thought as well was the revving up jumped the timing, but I checked it and it looks good, used the string method with the pulley off to get as accurate as I can.

Thanks for the wiring rec, I'll dig into that when I go to test wires with the volt meter
 

bobxyz

Board Member
Joined
Aug 29, 2014
Location
Boulder CO
Can you check the pin in the camshaft that keeps the gear in alignment too? When at TDC #1, the #1 cam lobes should both be up to left+right sides when viewed through the oil cap.

Cam Lobes at TDC.jpg
 

conehead

Member
Joined
Apr 21, 2021
Can you check the pin in the camshaft that keeps the gear in alignment too? When at TDC #1, the #1 cam lobes should both be up to left+right sides when viewed through the oil cap.

View attachment 20723
Good idea, I'll double check that. I have a compression tester arriving today so hopefully I'll have a chance to do that as well
 

ZVOLV

<Master Tech>
Joined
Nov 19, 2002
Location
California
FYI, you cam belt timing can be off and you can still get OK compression results.

No injector pulse has been verified. OBD mode doesn't count, but that at least let's you know the circuits are OK.

If it doesn't run on brake clean and spark is correct, that leaves mechanical.
 

conehead

Member
Joined
Apr 21, 2021
FYI, you cam belt timing can be off and you can still get OK compression results.

No injector pulse has been verified. OBD mode doesn't count, but that at least let's you know the circuits are OK.

If it doesn't run on brake clean and spark is correct, that leaves mechanical.
Can you check the pin in the camshaft that keeps the gear in alignment too? When at TDC #1, the #1 cam lobes should both be up to left+right sides when viewed through the oil cap.

View attachment 20723
ding ding ding ding! You guys rock. The camshaft pin has indeed sheared off. At first glance, I thought the cam looked fine, but your picture set me straight. It just didn't occur to me that the cam gear would still spin, but thinking about it again it makes total sense, especially at such low force like when turning by hand.

Thanks a million everyone, super appreciate the encouragement to dig further and not jump to my "I checked it so it's fine" conclusions.
 

ZVOLV

<Master Tech>
Joined
Nov 19, 2002
Location
California
IPD sells solid dowel pins. I think most of the time the failure is from DIY owners not getting the cam gear bolt to the correct torque since there isn't an easy way to lock the cam. I usually just slam the bolt tight with my 1/2" gun, but not so tight that it will break the bolt. I've also been known to lock the cam with a pry bar, but a cracked the casting once that way.

Glad to help! Good diag.
 

conehead

Member
Joined
Apr 21, 2021
IPD sells solid dowel pins. I think most of the time the failure is from DIY owners not getting the cam gear bolt to the correct torque since there isn't an easy way to lock the cam. I usually just slam the bolt tight with my 1/2" gun, but not so tight that it will break the bolt. I've also been known to lock the cam with a pry bar, but a cracked the casting once that way.

Glad to help! Good diag.

I was about to order up some of said dowel pins but found that a 13/64th drill bit I have is actually just about perfect, approximately 0.07' off from the 5-5.2 mm that I measured on the original dowel pin. Went to the hardware store and grabbed a couple for just under what ipd sells. 5 minutes with a cut off wheel, a drill as a lathe and some sand paper got me right about to the same spec as the piece I was able to extract. Tossed in it, 1/2 in impact like you said, lined everything back up and now she fires right up. So glad it's not some annoying electrical gremlin like I had thought.
 

Khrrck

Professional Amateur
Joined
Mar 11, 2015
Location
Beaverton, OR
It's probably fine in this application, I'd be a little cautious about using drill bits like that all the time though. A hardened tool steel like you get in a drill bit may be more brittle and likely to snap than a softer one.

That said, even if it breaks you can just repair it again easily enough. :)
 

bobxyz

Board Member
Joined
Aug 29, 2014
Location
Boulder CO
Glad you got it figured out and running again :)

I'm still stumped on why reving it up by downshifting on a downhill could shear the cam gear pin. <<< Can anyone explain this???

Is your oil light/gauge working OK? The only sheared pins that I can remember are from lack of oil due to either really bad maintenance, or the oil pump transfer tube o-ring seal popping out.
 

conehead

Member
Joined
Apr 21, 2021
It's probably fine in this application, I'd be a little cautious about using drill bits like that all the time though. A hardened tool steel like you get in a drill bit may be more brittle and likely to snap than a softer one.

That said, even if it breaks you can just repair it again easily enough. :)
Good point. I think last time I tightened the cam bolt, I definitely didn't tighten it enough, so hopefully this time it won't be an issue regardless of what material it is.
 

conehead

Member
Joined
Apr 21, 2021
Glad you got it figured out and running again :)

I'm still stumped on why reving it up by downshifting on a downhill could shear the cam gear pin. <<< Can anyone explain this???

Is your oil light/gauge working OK? The only sheared pins that I can remember are from lack of oil due to either really bad maintenance, or the oil pump transfer tube o-ring seal popping out.
Obviously I'm not the expert here, but, I would wager that because I probably didn't torque it enough years back when I first put the engine in, that over time, there was just a little bit of play and after many downshifts, burnouts, etc, that somewhat thin rolled pin just couldn't keep up. I do drive the car a bit hard, and the trans shifts pretty hard as well. Factor in me tapping the throttle on the downshifts to "rev match" and It starts to seem feasible that a sudden change in load would jerk it around a bit. I keep up on the oil and seals is really what I'm trying to get at, so I doubt lubrication is the issue
 

conehead

Member
Joined
Apr 21, 2021
Glad you got it figured out and running again :)

I'm still stumped on why reving it up by downshifting on a downhill could shear the cam gear pin. <<< Can anyone explain this???

Is your oil light/gauge working OK? The only sheared pins that I can remember are from lack of oil due to either really bad maintenance, or the oil pump transfer tube o-ring seal popping out.
Oh and my oil light does work, in that it comes on for a split second on start and the sensor is....recent. also I dig your profile pic. Loved that comic since I could read
 
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