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Followup To
Question -
96 Grand AM GT with 2.4L DOHC & 5 speed sat for a year at dealer with suspected ABS problem. Auction car I bought. Replaced fuel pump, heater core and intake cam seal. Car runs fine but has loud to moderate "slapping" noise that is RPM sensitive. It seems to be coming from the timing chain end of the engine and is not affected by oil weight. Virtually the same with Walmart 5W30 or 20W50. The noise will sometimes taper off to almost nothing then all of a sudden come back with a vengance. Was suspecting timing chain chain slap but can't see any problem there when enging running and chain cover loosened for viewing chain. Inspected crankshaft, rods, oil pump, and pump chain and although it seemed loose, there is no problem there. Adjusted chain tensioner to slightly tighten anyway. Cams, lifters and valves visually look ok. However, that was just a visual inspection. Noise could be coming from 1 or 2 cylinder area though. How do you check a hydrallic lifter to verify it is pumped up and working properly?
Also, any other ideas on what the problem might be other than lifters? And how do you check for those 'other ideas'?
Last is ABS problem. Module missing when bought and wire to passenger front wheel sensor was scrapped probably to ohm out I suspect. How do you check ABS sensors on wheels and do you have any info on voltages that should be seen at sensors with engine off or on? Basically, how do you troubleshoot ABS system?
Thanks for all the help. Bill
Answer -
Hi, if you had a lifter that is not pumping all the way up the valve would tap. What i thank is wrong with the engine is the timing chain. if im wrong that good. But if im right and the timing jumps it will cost you around 1000.00 buck, to get it fix. On the ABS this will have go to a repair shop that can diagnosed the brakes,
REPLY: Although the auto chain tensioner was extended to the maximum throw the cog gear would allow, the chain shows no indication of slap when viewed with cover removed and engine running. Replaced chain anyway and tensioner only half extended now. But, slapping sound still prevalent.
How do you test for hydralic lifter problem? How do you know they are fully pumped up and not causing "slap" of cam onto lifter head?
Or should I suspect #1 or #2 rod bearing? I have only found trace metal shavings in oil pan after pan removal. But, sound is definitely more pronounced with timing chain cover removed and subsequently seems to be coming through oil ports in lower end.
As for ABS, I have OBD2 scan tool but appears ABS isn't covered by OBD2. When vehicle is idling, what are the voltages that should be seen at wheel sensor harness and what should be ohmic value of sensor at wheel? Any idea? Again, Thanks for the help. Bill
AnswerHi, sorry for not answering you my computer was down, I would check all the rod bearing, with the metal in the pan this is a sing of rod bearing or main bearing is wron. The only way you can tell if the lifter is not working is that the valve would be tapping, Be cause the lifter is the rock arms on this typ engine. The wheel speed sensor, the ohms between terminals is 800 to 1400. between each terminal and ground is 15.000 ohms minimum.
