Mechanics

CHEVY TIMING MARKS CAN'T BE ALIGNED

1986 Chevrolet S-10

Engine Mechanical problem
1986 Chevy S-10 4 cyl Two Wheel Drive Manual 180, 00 miles

I recently had newly remanufactured Jasper engine (2.5L, F.I.) Installed in my truck. Installer told me it had no timing tab and that they set it by ear. Not good in my opinion; I'm a long time auto and do it yourselfer. I contacted and discussed with Jasper who sent them one and they installed it. Installer now says pullies must have been changed and it can't be timed with a light. Just turned it back to me that way. Went to a mechanic friend. We positioned top dead center of #1 cylinder and a made a mark on crank pulley at timing scale. When engine is started (and runs fine) the timing mark on the pulley (using timing light) is Way, Way off the scale. No way to accurately set timing. Could problem be the original distributor that's in new engine (or what)? Been at engine problems since 12/3 when installer received new engine; told me it was ready New Year's Eve at 5: 34. Told them no transportation to get there. Picked up 1/4 with all kinds of issues I've been working out myself. Installer is no help. Committed to fixing it myself with other help. Have been iin close communication with Jasper who says distributor is the only thing left. Help? Ron
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RONREYNOLDS
January 29, 2010.



Did you do this? IGNITION TIMING 1. Install timing light with adapter between No. 1 spark plug and No. 1 spark plug wire, or use inductive pick-up. Do not puncture wire. Run engine until it reaches normal operating temperature. 2. Electronic Spark Timing (EST) must be in Bypass Mode to check ignition timing. Ground terminal "A" to "B" at Assembly Line Diagnostic Link (ALDL) connector. 3. Place transmission in Neutral (man. trans.) or Drive (auto. trans.). Set average timing of cylinders No. 1 and No. 4 to specification. Adjust if necessary.


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Set to 8 degrees BTDC @ 650 rpm

Merlin2021
Jan 29, 2010.

Tiny
RONREYNOLDS
Jan 29, 2010.
Thanks for your reply. 1) We used an inductive timing light; not connected in series between the plug and wire. Did not puncture wire. Engine reached normal operating temperature. 2) I don't know if my friend (the mechanic) bypassed the EST and grounded the terminals " A" and " B" at the ALDL connector but I will ask. 3) Manual transmission was in neutral. I don't understand: " Set average timing of cylinders No. 1 and No. 4 to specifications". We were dealing only with cylinder #1 and could not get the timing mark on the crankshaft pulley to come any closer than several inhes from the timing index scale bolted to the block. As for " average", I don't follow unless you're referring to the timing mark on the pulley fluctuating and using that fluctuation range within which to take an average against the index scale. Is that correct? I will ask my friend about that also. I also had no idea that #4 cylinder was to be involved at all. I will pass all this to him and one of us will get back to you. Thank you. Ron Reynolds

Tiny
RONREYNOLDS
Jan 29, 2010.
I checked with my friend and he says everything was done that you brought up in your answer. You didn't say, but my information also asked if my old, original distributor which is now in the new engine could cause this? I did provide a new ECM from O'Reilly's Auto Parts when the new engine was being installed.

Tiny
RONREYNOLDS
Jan 29, 2010.
Eithe the distributor, or maybe the timing marks on the chain are off? If you set number one to TDC, mark on the crank should line up with the pointer, and number one should be firing according to the rotor in the distributor, another possiblilty is you put the pointer in the wrong place, how does it idle? Run? Is there a performance issue?

Merlin2021
Jan 30, 2010.
Hello Merlin; The 2.5L engine does not have a timing chain; it has gears. 1) Could they have been installed incorrectly by Jasper and cause this? I would think that was impossible 2) Many years ago (I've had truck for 18 years) I had A/C installed on the truck from one in the junk yard. Mine came without air. After new engine installer first gave me the truck back after new engine was installed, they said that it had no " timing tab" and they " set it by ear, and the tabs are impossible to find". I know better. At another point one mechanic told me that it " broke off" and he felt bad about it. Offered me no way to correct that. I called Jasper who sent installer one; I took truck back and they installed it. Still could not time the engine with marks on the pulley; now they say puliey must be wrong (from the truck in junk yard with the A/C) because mark on it won't line up with the index tab. ***** Setting it by ear does make it start, run and idle fine with no performance issues; other than idles too high (850rpm) and no way to lower it (manual adjuster is all the way). ***** Some people would be satisfied with this; just to do it by ear and get it fairly close. But with a new eigine, and all the additional parts I've put on, I cannot accept it until I can get the marks to line up and time it right. (New parts: radiator, water pump, starter, alternator, plugs, wires, dist. Cap, various sensors, water temp senspor, PCV valve, coil, oil sending unit, etc. Virtually everything except distributor. NOTE: We did set #1 TDC and MADE a mark on the pulley, within the timing tab scale bolted to the block. When started and running, THAT mark is several inches away from the timing tab. ***** I do NOT know if this is the proper place and way to reply to you. I find no instructions on 'how to use' the 2carpros site. From my screen, I see two possible ways, but neither one is clear. Can you direct me where to find out how to use this site? HELP? Thank you. Ron

Tiny
RONREYNOLDS
Jan 30, 2010.
EXPERTEC TSB TECHNICAL SERVICE BULLETIN Reference Number(s): 89-143-6A,  Date of Issue:   03/31/89 Related Ref Number(s): 89-143-6A ARTICLE BEGINNING INSTALLATION OF TIMING - INDICATOR/SET Model(s): 1985-89 Chevrolet/GMC S, T, M Truck With 2.5L (VIN Code E) Engine Bulletin No.: 89-143-6A Date: 03/31/1989 SERVICE INFORMATION TO: ALL CHEVROLET DEALERS When completing the assembly of a partial engine, please be aware of the following: 1. 1985 and 1986 2.5L truck engines - • The side-mounted timing indicator and plate assembly with attaching studs, as shown in Fig. 1 , should simply be transferred to the new partial engine. 2. 1987 through 1989 2.5L truck engines - • The set screw, as shown in Fig. 2 , needs to be removed from the new partial engine assembly. Apply Loctite (R) 242 or equivalent to the set screw and reinsert into the block. The set screw should be seated flush to the boss surface. This step is required for two reasons: A. The set screw is loosely threaded into the partial engine block as shipped from GMSPO and B. The threaded hole breaks out into the coolant jacket and requires application of a sealant to the set screw to prevent a coolant leak. This step must also precede installation of the air conditioning compressor support, as shown in Fig. 2 , if so equipped. BULLETIN ILLUSTRATION LIST Fig. 1: Graphic Fig. 2: Graphic


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Maybe this wasnt done? Timing for any engine is arived at by the factory on an average of 10 engines and where the run best, it does not mean some engines will NOT run better at different mark! Could an 87 indicator been installed on your engine?
You are replying the right way, just click on the answer question button at the bottom of a question.

Merlin2021
Jan 31, 2010.
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WOW WOW WOW! Merlin, I think you may have hit the target, my friend. This is Sundy and I've not been able to reach my mechanic friend, but will talk with him as well as Jasper Engines tomorrow. All along Jasper has been saying (according to the local installer who is not trustworthy) that there is only ONE timing index plate for the 2.5L engines. Your bulletin information proves that wrong. The indicator NOW on MY 1986 engine is clearly in the front, as the diagram shows is for 1987-1989 engines. The area shown in the diagram for the 1985-1986 engines is side-mounted, on the driver's side of the engine and would place the index in the area where the pulley mark has been appearing with the timing light. I'm praying very strongly this is it! Will let you know for sure what I find out. In the meantime, as I'm restoring my truck (I've had for 18 years). 1) I want to add gauges instead of just the idiot lights. I've located a gauge cluster on ebay which says it's for an 8 cylinder. Do you know if it will work (or can be configured) with my truck, being a 4 cylinder? My truck did not have A/C from the factory; I added it about 16 years ago and have simple lived with the engine dying at idle due to the compressor drag not being compensated for. Recently my same mechanic friend ran a wire from the computer to a place on the A/C and now the engine doesn't die from too low RPM when idling. Can something similar be done with the gauges to make them work? 2) Finally, we've been unable to lower the RPM below 850 (with the plug removed for the manual adjustser, which is adjusted all the way). I want to lower it to the 650 range that's proper. What do you think it would take to correct it? If your answers prove correct, I'd like to send you a special bonus (in addition to the donation I've already made) if you can let me know your email address or phone. Mine is 423-899-2074, and REYNOLDSRA1@AOL. Ron

Tiny
RONREYNOLDS
Jan 31, 2010.
I believe the 8 cylinder panel will work OK, most testing equipment adjusts to test 4/8 or 6 cylinders.
Email is
merlin2021@comcast. Net
I will look into the idle adjustment for you and get back to you. Also take note that the pulleys are different as well?

Merlin2021
Jan 31, 2010.
HOT (SLOW) IDLE RPM 1. Remove air cleaner and gasket. Plug TBI unit vacuum port for THERMAC (Thermostatic Air Cleaner). Remove T.V. cable from throttle control bracket. Connect tachometer to engine. 2. Disconnect Idle Air Control (IAC) connector. Start engine and warm to normal operating temperature with transmission in Park (auto. trans.) or Neutral (man. trans.). 3. Install Air Passage Plug (J-33047) into throttle body idle air passage. Ensure plug seats air tight. See Fig. 2 . 4. If plug covers throttle stop screw hole, remove plug by drilling 5/32" hole through casting into plug. Using 1/16" punch, remove plug. 5. Using Torx Bit No. 20, turn throttle stop screw to adjust slow idle to specification. Turn off engine and remove air passage plug from throttle body air passage. 6. Install T.V. cable into throttle control bracket. Install IAC connector. Seal throttle stop screw with silicone sealant. Install air cleaner and gasket.


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Merlin2021
Jan 31, 2010.
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