I recently replaced the head gasket on my Honda Accord. The cylinder head was tested at a machine shop and they also replaced the valve seals.

I didn't do any work to the cylinders, except use degreaser to clean off the piston heads.

I got the engine put back together, but was unable to get it to start.

I took the car into Pep Boys for an Engine Diagnostic.

They said that they tested the battery, spark plugs and fuel.

The mechanic noticed that the top cover for the timing belt was off and jumped to the conclusion that the reason the car wouldn't start was because the timing was off and were going to charge me $700 to replace the timing belt. I explained to the mechanic the work that I had done and that I had removed the top cover and just hadn't replaced it yet. Still he said that the timing must be the problem but he couldn't tell for sure without removing the lower cover and charging me a lot of money.

As an aside, I feel that I received very poor service especially for the amount of money ($100) this engine diagnostic cost and won't be returning there for auto service. The clerk was rude to me and I overheard them call my car a piece of $#!*. It probably is, but still they shouldn't have said so with me standing right there. I'm pretty sure the mechanic was wrong about the timing being off. You can check the timing without removing the lower cover using the sights on the lower cover and the markings on the crankshaft pulley. The mechanic made me second guess myself. I rechecked the timing marks and they all lined up and even removed the lower cover and checked the marks on the timing belt drive pulley and balance belt drive pulley even though they're all connected with the same key to the crankshaft. I removed and replaced the timing belt following the manual and it still wouldn't start.

What are some other things I can check assuming I can trust the mechanic to have tested the basics like the spark plugs firing and the engine getting fuel?

I adjusted the valve clearances and the valves are opening at the correct camshaft positions.

I think I'll do a compression test, just to make sure even though the compression was good before this service and the cylinder head was tested at the machine shop.

I could replace the Crankshaft position/TDC sensors, even though I just put new ones in. I have gone through the experience of buying a new faulty camshaft position sensor before for a different car.

The only other thing I can think of is to test the ignition timing with a timing light. Ignition timing could be off since I removed and replaced the distributor.

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    What customer service people fail to realize is that customers pay for their salaries. If no one comes to their shop they go out of business! Your car is important because it's your transportation and they should treat it in that regard. You are right about them needing to keep their opinions about your car to themselves. Commented Dec 31, 2015 at 16:49
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    I got it running today. It was an electrical ground that I must have disconnected between the throttle body and brake booster. I remember thinking of double checking that ground earlier but thought there was no reason I would have disconnected it since it's so far out of the way. Thanks for your answers and reminding me to check the electrical connections again.
    – willpb
    Commented Dec 31, 2015 at 18:45

4 Answers 4


You need Spark, Fuel, and Compression for an engine to run. Since this engine was just reassembled, there is a lot to question.

Spark -
rotor position - beware of caps where the points are not "straight through"
plug wires in the correct position
timing - may need play with it a bit
coil - ensure it is firing
spark plug firing - use a jumper to connect the base of the plug to a unpainted part of the engine. watch while someone cranks
spark plug gap

Fuel -
Fuel Pressure - without a gauge, you can hit the Schrader valve to see if fuel squirts out.
check if the plugs smell like fuel to ensure the injectors are firing
you can try spraying starting fluid in the throttle body

Compressions -
Test the compression on each cylinder. should be at least 120psi
If it is less, either the head gasket didn't seal, a valve is bent, the valves are adjusted too far, or you have a ring issue.

Another couple points
double, triple, quadruple test every single electrical connection and vacuum line
did it run before you took it apart? You mentioned the cam sensor, do you still have the old one you can try?
grounds - are they all connected?


Engines need 4 things to run- spark (at the right time), air, fuel, and compression. A lot of things can conspire to deny some of those things. Don't just start shotgunning parts, that gets expensive real fast. Take a few moments to do diagnostics first. Once you find the category of problem, you've eliminated 3/4 of the possibilities, and tracking it down becomes easier.

By all means start with the compression check. While you're at it, you have the spark plugs out, check each one for spark as you crank the engine. Exactly how this is done depends on if your vehicle has plug wires or coil packs, but no matter the setup, it can be done.

Check if the fuel injector(s) are spraying fuel.

Finally, I wouldn't trust the AVERAGE chain shop with a head replacement, let alone diagnosing a problem like this. (Yes some chain shops are better than others, and some have special competencies, but most exist to do bread and butter maintenance). You're already a handy person, follow through and trust yourself that there are only so many things to check. Check the easy stuff first. There's plenty of help here, on Youtube and vehicle specific sites on how to make diagnostics easier.


It's certainly worth checking the ignition timing - one obvious possibility (though I'm sure you've checked this) is that the timing is 180 degrees out, so it's firing at the end of the exhaust stroke instead of the compression stroke.

Otherwise, have you done a compression test since reassembling? I doubt there would be any problems there, but might be worth a quick check. Also check the fuel supply - does it smell like unburnt fuel is coming out of the exhaust? Check for any loose connections, blocked lines or airlocks in the fuel system. Check that the fuel pumps are working too.

  • I double checked the ignition timing and made sure it wasn't 180 degrees off. I can smell unburnt fuel coming out of the exhaust. I can hear the fuel pump working. I'll try a compression test next, and check for loose connections.
    – willpb
    Commented Dec 30, 2015 at 14:52

I know this is a very old post, but I thought I'd put this here for others to use:

I had the same issue with my '97 Accord after a head change, and it turns out there is a ground wire that goes to the intake manifold (Near the brake fluid reservoir) - Once I bolted the wire back down, the car started right up - Check this ground before anything else if having no start issues after head work!

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