Detonation (knock) and Timing

xr4tifan · Post by **xr4tifan** » Mon Oct 25, 2004 7:31 pm

I just had to replace the thermostat and water pump and since I discovered my passenger side motor mount had lost all three bolts (two broken off in the block) I replaced the motor mount in my '88.

I figured while I had all this stuff apart, I'd clean it up a bit so I power washed the engine after sealing every opening I could think of. I put everything back together including new plugs, new wires (yes they are in the correct firing order), new dist cap & rotor. Put on a few fancy blue silicone vacuum hoses. Painted some engine compartment parts blue. Installed a new water temp gauge (the one on the dash didn't seem to be working since it never got more than 1/8 of the way up. Took out the heater valve using some pics and instructions I got from the forum. New belts and upper and lower rad hoses. Changed the oil and filter. Started it up and now I get detonation (knock) at the low end of the rpm range!!! (Can't give the exact RPMs since I still need to either install a new tach or fix the one in the dash.)

I suspect it may be the timing but I don't know how that could have changed since I did not mess with the distributor! Car doesn't have a timing belt cover so I don't have a way to check it! Is there a way to check the timing without the cover or could there be something else causing the knock? All of the vacuum hoses seem to be on correctly.

Stumped in Des Moines

Post by **John Brennan** » Mon Oct 25, 2004 8:10 pm

Without some means of measuring timing at the crank, you really can't. Do you have the rear cover on? If so, I have a good front cover here ready to ship if you want. If not, I have a rear cover also; would just have to remove it from the block it's on.

Otherwise, you could get a nice metal indicator from OPMD.

xr4tifan · Post by **xr4tifan** » Tue Oct 26, 2004 9:02 am

Hey John. Is that the front cover we discussed earlier in the month? Is it still $30 S&H? I'll put a check in the mail today if you give me your address. Here's my address:
Thomas Frazier
5620 Aspen Dr.
West Des Moines, IA 50266

Thanks

Post by **John Brennan** » Tue Oct 26, 2004 4:55 pm

PM sent.

xr4tifan · Post by **xr4tifan** » Fri Oct 29, 2004 12:36 pm

If it's not the timing, what else could be the cause?

SuperCollasus · Post by **SuperCollasus** » Fri Oct 29, 2004 1:32 pm

Have any of the new vacuum hoses collapsed? What is the condition of the fuel pressure regulator?

If the car is running sluggish or seems to fall dead during shifts you may want to start looking at your fuel. If you are not getting enough fuel you might be running lean and could relate to the knock. If that doesn't work look through this thread.

http://www.merkurclub.com/forum/viewtopic.php?t=2782

Good wires, rotor/cap, fuel filter, intake clean and vam clean out should be in order as a part of regular maintenence.

http://www.merkurclub.com/forum/viewtopic.php?t=2782

xr4tifan · Post by **xr4tifan** » Fri Oct 29, 2004 2:06 pm

Would anything else come into play if car is an automatic?

xr4tifan · Post by **xr4tifan** » Sat Oct 30, 2004 3:00 am

OK! Timing right @ 10 degrees BTC. All vacuum hoses AOK! Still getting knock even before car heats up! Help, I don't want to have to take it to the FORD dealer!!!

HEEEELLLLPPPPP!!!!

Post by **John Brennan** » Sat Oct 30, 2004 3:31 am

First, are you sure the cam timing is correct? The belt may have jumped a tooth or two. Be sure that is set correctly. Tensioners get old, and need to be replaced-- most say every other new timing belt, or 100,000 miles. Make sure you have enough tension on the belt, too.

Sometimes, I've run into a batch of crap gas that causes a little knock-- I've tested it by throwing in a little octane booster, which usually makes it go away. Have you run codes? Do that, see what you have, then clear out the codes and run it a couple of days. See if that doesn't clear it up, then run codes again and see what you've got.

Your timing cover's on the way, as I've said in your PM.

xr4tifan · Post by **xr4tifan** » Sat Oct 30, 2004 10:16 am

I took the bottom half of the busted timing cover and checked the timing. Cam timing is OK. Marks line up. I'll throw some Octane Boost in the tank and see if that takes care of it. I'm also going to do a vacuum test to make sure I haven't forgotten a hose somewhere.

As a novice with just enough knowledge to be dangerous. I haven't ran the codes. Where can i get a code reader and where does it get hooked up. I'm used to working on cars with points & checking dwell etc.

The strange thing with this whole problem is that it did not exist prior to changing the oil,hoses, etc. Is there any way water could have gotten into something that would cause this problem?

Thanks for sending the cover. I'll let you know when it arrives.

SuperCollasus · Post by **SuperCollasus** » Sat Oct 30, 2004 1:29 pm

BTW: Check the gap on the plugs make sure they are about .32-.34. Re check the boots on the wires.

Post by **John Brennan** » Sat Oct 30, 2004 5:25 pm

A code scanner can be obtained at just about any major parts house for about $30-40. I'm betting you have just overlooked something simple, like a hose connection, or a loose bolt somewhere (I found one once on my turbine housing-- backed off and fell out!), and that's why I suggested checking the cam timing, 'cause that'll cause that. Look over everything very carefully, using a flashlight and a mirror to look under things.

xr4tifan · Post by **xr4tifan** » Sat Oct 30, 2004 7:32 pm

OK. Just checked timing on all 4 cylinders. 1 and 4 are right at 10 degrees. 2 and 3 are no where in sight. Is there any reason this would/should occur? As far as I remember, all should be in time.

Getting really frustrated now!

Colin · Post by **Colin** » Sat Oct 30, 2004 10:34 pm

He put the inductive pickup on the individual plug wires.. that's why 1 and 4 appeared at 10 BTDC and 2/3 were elsewhere.

Colin · Post by **Colin** » Sat Oct 30, 2004 10:38 pm

SuperCollasus wrote:Check the gap on the plugs make sure they are about .32-.34.

That's a mighty large gap, doncha think?