Cam Synchronizer, Driveability Issue

Okay, so i had the infamous chirp with my '98 Windstar (3.8, 145k), and I had a shop replace the cam synchro. However, after a couple days of driving on it, i started noticing that when i would hit the gas harder than normal (from a stop only), the engine would bog down first before unleashing its many horsepower. :wink: I brought it back to the shop and they said they lined everything up as they should have and even used an alignment tool to position the new one. The van runs great, except when you punch it from a stop (i.e. starts fine, doesn't run rough). The shop said they didn't know what to do and told me to let them know if it gets worse (probably won't go there again). Afterwards, I messed around with the alignment of the synchro to see if I could influence it for the better (or worse) to not much avail. So my question: is there something else they could have disturbed that would cause the engine to bog down as I've described? I'm at a loss here and i feel that it's a safety issue if you need to get out into traffic in a hurry. Many thanks!

My guess would be they used the wrong plastic alignment tool for your particular engine series (there are several different alignment tools ... it has to be the correct one) ... or they did not have the crankshaft on TDC/combustion-stroke for the #1 cyl.

I often use a plastic rod/probe to stick thru the #1 spark plug hole, rest it on top of piston ... and "feel" the piston travel up-and-down, as the crank is revolved, to make sure the crank is at TDC. I do this to verify that the markings on the crank pulley have not shifted and are still correct for the crank.

If the valves are closed and the piston is at TDC in the #1 cyl ... then the alignment tool can be used for best timing results.

Thanks for the input - I will give that a try. One thing, can you explain how to find TDC of the combustion stroke? That is, how can you tell if the right valves are open/closed? Thanks.

I thought you might come back with that question ... it is a good one. The crank has to revolve twice so that all cylinders can complete an exhaust stroke and a combustion stroke. When we speak of "TDC" of an engine, we usually are referring to the #1 cylinder being at TDC on its combustion stoke. Since the piston comes up to TDC on the combustion stroke, and on the exhaust stoke .... How can it be determined which stoke it is on? Well, the biggest clue is both the valves are closed on the combustion stoke at TDC ... but then, how do we determine that? ....

#1: Remove the valve cover and look at the valves. A bit of work, but the absolute sure way.

#2: My preferred way ... not as absolute, but good enough. With the spark plugs removed, bring the #1 piston to TDC. With a trigger type air valve attached, cram your air compressor hose into the plug hole and give it a blast. Wrap a shop rag around the nozzle to make a good seal.
Roll the crank one whole revolution ... the #1 cyl is back at TDC. Do the air nozzle blast again.
You should be able to determine in which case the valves were closed ... by the difference in air flow resistance.

Thanks for the tip. That sounds pretty strainghforward. One question, where can i get the cam synchronizer alignment tool? A google search didn't lead me anywhere that looked very reliable. Thanks.

http://www.automotiveforums.com/vbulletin/showthread.php?t=567975&highlight=synchronizer

OTC tools are sold at a number of old auto parts suppliers ... the independent ones, not the big-box stores such as AutoZones, Pepboys, AdvanceAuto, etc

.... Looks as tho OTC 6469 will work for you.

Looks like Summit Racing carries it:

http://www.summitracing.com/parts/OTC-6470/

Looks like Summit Racing carries it:



I bet they do carry "it". But, beware, he does not need #6470 .... IIRC !! I believe he needs #6469.

I don't know what the difference is exactly, but the engine did go thru some mechanical changes in 1999. In fact, there's a chance that this difference was not noticed by whoever has worked on the car up 'til now ... causing the poor performance. (I just hope the correct year-model synchronizer was purchased. ??) The old synchronizer could probably be used again after a good lubrication. I have disassembled my old one and installed a grease fitting ... not a job for the faint-of-heart. Haven't installed it yet.