Engine ticking

STEVE ADOLPH

MEMBER
2003 MAZDA PROTEGE
2.0L
4 CYL
FWD
MANUAL
161,000 MILES

So I bought this car from a mechanic off of craigslist who had claimed in the ad that he had replaced the car with a bunch of new parts. The parts mentioned in the ad included the following, four new tires, timing belt, water pump, serpentine belts, radiator, engine cylinder head, head gasket, head bolts, valve cover gasket, catalytic converter, O2 sensors (both front and back), ignition coil packs, spark plugs, front rotors, front brake pads, and front calipers. The car has a clean title and has passed smog check, also has a fresh oil change. The first thing I noticed was the car had a ticking (similar to a sticky hydraulic lifter), I looked at the engine bay and noticed the new head because it was shiny. I thought about mentioning the ticking noise right off the cuff to the owner but did not and never asked about it. The car was already warmed up. I then proceeded to take it for a drive. It drove just fine and I drove it up to forty five miles per hour to test it and did not go any faster and then returned back and bought the car. It has been three days now and I have had more time to take closer inspection of the car. I did not have my own mechanic inspect it. Looking back I could have probably gotten the car for several hundreds less. I have verified that that rotors, pads, calipers, radiator, catalytic converter serpentine belts, front O2 sensor, tires, spark plugs and ignition coil packs are all new. What has me concerned is the engine cylinder head, whether the inside of the head (camshafts, valve stems, hydraulic lifters, and so forth) are also new. I am worried that the engine head has used parts inside but outside casting is new. How could the car have a ticking or sticky lifter if the engine cylinder head was truly "all new"? I have done some reading on forums and heard that the possibilities for the ticking could be the fuel injectors (though I doubt this.), Butterfly valves in the intake manifold, or hydraulic lifters. I welcome any answers, questions, or opinions. Thank you.

1 Reply

CARADIODOC

MECHANIC
33,752 POSTS

First of all, it is very unlikely the cylinder head is new. It is not practical to order a new head. That would have to come through the dealer and would be horribly expensive. Instead, we get rebuilt heads that were professionally rebuilt by a specialty company. The service includes cleaning the casting which makes it look new. Valves and seats are reconditioned so they seal properly. Valve springs are tested for strength and free length, then are replaced only if necessary. Valve lifters or lash adjusters may be not included with the head. Some are complete bolt-on assemblies with overhead camshafts already installed. Some are basic heads that have all the delicate machine work done, then the mechanic installs the reusable parts. How the head is ordered depends on what was wrong with the old one.

Many people become concerned when they hear the clicking of fuel injectors, but there are also emissions-related valves that click on and off. Some cycle about once per second and can be pretty loud. A clue is injectors will click faster when engine speed increases. Emissions valves click at steady rates. Regardless of the cause, you should not be able to hear anything clicking when the hood is closed and the windows are rolled up. With the windows open, you might hear an emissions valve, but if it is annoyingly-loud, suspect it is mounted in a rubber isolator that has deteriorated. If the valve hits a metal bracket, the noise will be amplified.

Worn and stretched timing chains can rattle against the housings. Your engine uses a rubber timing belt, so that is not a concern. I would suggest having another mechanic listen to the sound to determine the cause. Given the apparent quality of the work, it sounds like you are hearing something that is normal and nothing to worry about.