Greetings,
I am below a newbie. While I have done work on my engine I am a rank amateur.

The reason I am posting. I have a 1993 2 wheel drive pickup (not an off roader or mod) that I have an unhealthy love for It's been a great runner. I made the mistake of having an incompetent mechanic do PM timing chain replacement about 5 years ago. I found out much later that he hadn't replaced the guides! This caused the chain to wear through the chain cover at the part where the coolant tube runs. Wore through and allowed coolant into the oil. I took the engine to a highly recommended, in the biz a long time, mechanic. He replaced the chain, gears, guides, and cover. Truck ran great for a year and a half. Then it started exhibiting loss of power/rough running, this increased dramatically very quickly. Checked the oil, theres the coolant Had it towed to the mechanic and after he made me wait forever he finally repaired it. Said it was the oil channel to the chain tensioner (gunked up and caused insane chain to cover wear, same problem as last time).

Now after all that setup, here is my question. I picked the truck up today (got all the old parts) checked the oil and coolant levels before driving it just to be safe. Drove it about a hundred mile, ran great. As i was heading home I went down the highway (75 miles per hour) still ran great, but when I was decelerating at the off ramp the engine made a single well defined loud knock sound (knock-knock) at the tail end of the engine revving down, then idled fine. Drove from light, ran fine, let up on gas (doing this with clutch free wheeling) same loud knock. Got home and checked oil WAY LOW, about 1.5 qts. Cannot see in obvious leak (will check again in the AM). I was wondering if anyone can point at some possible causes. I would like to have an idea before I contact the mechanic as I'm a little wary... Any help would be truly appreciated.

Thank You,
Kevin

 

The knock is somewhat symptomatic of a chain guide failure. give the past problems with timing chains, i would pop the valve cover off real quick and take a look.

On the oil loss, if it actually lost it, it either burned it or leaked it. no real good place in the motor to "hide" it.

 

Thank you for your reply. As I said I am not an accomplished mechanic, although I have successfully installed a new head gasket last year. This truck repair has driven me nuts because the mechanic has taken forever and then the repair failed almost immediately. I've read on the internet the exact procedure for this repair and if he doesn't get it fixed correctly this weekend I'm going to have to bite the bullet and do the work myself.

Again Thanks,
Kevin

 

post up what you find. we can help!

 

I finally got the mechanic to work with me. The failure of the timing chain guides had allowed anti-freeze into the oil pan. This of course isn't healthy for lubrication, and it had rolled one of the rod bearings (as that had lost the burnish). So! I'm going to pay to have the crankshaft resurfaced and for the rings/parts and he is going to do the labor no charge.

Thank you for your responses
Kevin

 

no problem! hopefully you get it back up and running soon!