A journey through the engine - Update 2

[skyerunner]

Hi All,
It's been a while since I've been off the forums, and finally I got an issue I can ask you all about!
Some background, I got this car from my sister for $1, and it used to be my grandma's before that. It's been on way more adventures than I can count, and currently lives a great life in Yosemite National Park. It has about 250,000 miles on it and in all that time has never broken down, until now. The last major repair I did was replace the clutch in Petros' garage a few years ago... The other day driving down the hill to work and the engine suddenly started making a quick knocking noise. Soon after it started belching grey/white smoke. I drove it another 8ish miles to where it's been parked & am finally getting time to take a look.

Tercel_JB.jpg

Symptoms: Grey/white smoke, knocking, loss of coolant, with maybe some oil in the coolant overflow.
The knocking has gotten quieter, to almost not noticeable. When I pull spark plug wires, they cause a drop in rpm evenly, so it doesn't seem to be at much of a power loss. The radiator has a crack that probably accounts for the loss of coolant.
So today I started pulling it apart. First, the spark plugs are f*&$3. Plug #3 (the really black one) is missing half the ceramic insulator and I'm worried that is what broke, fell into the cylinder, and maybe gouged it (#4 broke while removing it). This is dumb, but those plugs are ~60k miles old, shoulda replaced them sooner.

Tercel_JB-2.jpg

I then pulled off the valve cover, but it got dark. No valve springs were broken. I'm planning on pulling it apart down to the head tomorrow.

Tercel_JB-3.jpg

I'll be continuing to work on this and post over the next few days, but any advice and recommendations would be much appreciated!
JB

[dlb]

have you done a compression test?

the great and white smoke definitely points to head gasket but the knocking is odd. probably is from the broken spark plug, like you mentioned. i would do a compression test just for knowledge's sake and then pull the head. inspect for deep gouges in #3 cylinder if that's the one that had the broken spark plug.

[keith]

Check ebay for good used or reman engines. I once got a reman 4AC longblock from a National Reman company located in Springfield, MO that supplies remans for some of the autoparts stores. They had an overstock and I got a $1400 engine for $250. I put a Weber on it, then spent a lot more money on 14" wheels, new struts and shocks, brakes, transmission, wheel bearing, etc right before it got wrecked.

Did I meet you this summer at an inn on Mono Lake?

[Petros]

smoke, loosing coolant, and oil residue in the coolant...all point to a head gasket. those spark plugs look older than 60k miles. I had to once pull spark plugs from an engine that were in there for well over 100k miles, I thought they were going to break off in the head! I should of poured sine penetrating oil down the intake and sloshed it round inside, plus on the outside.

Slight damage on the piston top and underside of the head will not cause any issues as long as it did not crack or penetrate the piston crown or the water jacket in the head.

The head has to come off it sounds like, so we will know more once we can see inside the combustion chambers.

[skyerunner]

Hi All,
Keith, I bet we did meet over at the Mono Inn a few months ago!
I looked into new engines, but they were running about $1500 from the phone numbers I got around here. I went to the Pick and Pull in Modesto today and found an '87 Tercel Hatchback with 68'000 miles on it. I started pulling off the head and after working all afernoon found that the whole engine would be cheaper than the head and add ons - so I'm going to get the new engine in the AM. I figure at least it's worth having those parts around off a really clean looking engine just incase, and for $310 that's alot -> (see link http://hyperboleandahalf.blogspot.com/2 ... thing.html) better than the other options. I'll post photos of the new motor in the AM.
Until soon,
JB

[skyerunner]

Oh, and if you all want to see a short video I made featuring my little tercel, check this one out:
http://vimeo.com/50570964

[keith]

We did the Bristlecone pines earlier that day. What a drive up to them. It was all my Saturn could do to pull some of those grades. its got 265k miles on it. I know the Tercel 4wd that we had would have really been taxed when it had the 3AC engine, it would have done a lot better with the 4AC and weber.

[Petros]

I heard from Skyrunner today, the news is not good. He got the head off and it sounds like the exhaust valve broke up, and the pieces did a lot of damage to the piston, head and bore. That was what likely damaged the spark plug. he is at his local picknpull today, getting a low miles engine out of a Tercel there.

[irowiki]

Wait, 87 Hatchback, isn't that a gen 3?

[rer233]

I heard from Skyrunner today, the news is not good. He got the head off and it sounds like the exhaust valve broke up, and the pieces did a lot of damage to the piston, head and bore. That was what likely damaged the spark plug. he is at his local picknpull today, getting a low miles engine out of a Tercel there.

Sounds like a real bummer- detionation?? Just one more reason to run premion gasoline- as pricey as it is- it's still cheaper than engine parts- and a DAMN site easier to install!

[Petros]

It has nothing to do with detonation or octane rating on fuel. This happens when you set the ignition timing at the emissions determined 5 deg BTDC, not all of the mixture is done burning when the exhaust valve opens and very hot combustion gasses flow past the exhaust valve, eventually causing overheat damage, and valve failure. I have seen it happens lots of times, sometimes if you are lucky only a peice of the exhaust valve breaks off and goes down the exhaust pipe, but other times the piece, or sometimes the whole valve head, falls into the combustion chamber and than gets pounded to bits by the piston. It only takes a few Millie seconds to trash an engine. I have seen several Tercel engines with the exhaust valve head imbedded in the piston top, and another one where the exhaust valve fell free and than the piston drove it up through the head, through the water jacket and into the area where under the valve cover. Not a pretty sight.

Always run your spark ignition at 10 deg BTDC, it will greatly cool the exhaust temps and keep all of the exhaust valves and seats in better shape. it will also improve power and fuel economy too.

[keith]

I kind of agree with you but not completely. Retarded timing is not good for the exhaust valves, but I think the bigger problem is that over the years, the mechanical advance starts sticking and no one notices that. At idle, 5 deg BTDC is plenty, the exhaust gasses have plenty of time to burn, but at 3000 rpm, the time to burn is only 1/4 that of 750 rpm. This is where the timing becomes very critical. High RPM at high vacuum really needs to have a lot of advance as the flame front really moves fast so the vacuum advance is also critical, but not quite as much.

I don't see anything wrong on cars built before the knock sensors were added to use a few extra degrees of advance on idle, nor do I see anything wrong with using the factory specs, but the mechanical advance needs to work per specs and that means getting a little oil onto the weights and springs every once in a while. I prefer to use a little synthetic oil every now and then.

If the mechanical advance is not working properly, then advancing the timing at idle may not save the valves.

[dlb]

to further on what keith just said, this is also part of the reason to have a properly working vac advance system. advancing the base ignition timing by 5* is good but having it advance the intended 8* at idle and 20* at hwy cruising when both the vac advance diaphragms are working is just as, if not more, important.

[Petros]

what you say is true, andof course all of the other systems must be working properly as well, if neither advance is working that you compound the problem. You are assuming that when you damage the exhaust valves there must be something wrong with the advance, I have not found that to be the case in the engines that had badly damaged exhaust valves that I had a chance to examine, one I rebuilt and is the one in my current daily driver for the last 100k miles. The only thing they had in common was over about 150k miles, likely ran their whole life at 5 deg BTDC. I had also burned and damaged two exhaust valves on my own engines when I set them at 5 deg, I have not had any damaged exhasut valves since I have been setting them at 10 deg BTDC.

If the mech advance is not working it will get really poor fuel economy and it will be way down on power, so it seems the owner should have a clue that some thing is not correct. The first 3 or 4 cars I have owned did not have a vacuum advance at all, never burned exhaust valves, and their static spark timing was typically 16 deg and 22 deg BTDC, plus all had mechanical advances, both they got great fuel economy and none had ping or pre-ignision on pump gas. At part throttle conditions or idle you are not burning a lot of fuel and the exhaust will not be that hot anyway, at full throttle the vac advance is not engaged since manifold vacuum is very low.

[keith]

My first engine burned an exhaust valve at around 300k miles, but it was due to my not checking the valve lash. The engine had always been run at 5 deg BTDC but it did have stuck weights when I got it, don't know how long they were stuck but that was at about 192k and the vac advance didn't work. I put in a reman distributor at the time because the center shaft bearing was worn out.

Just before the valve burned, I noticed a slight miss at idle so I checked the valves, that one was so tight that the valve wasn't closing. I adjusted the valves, all were tight, and it took care of the miss so I thought I dodged a bullet, but about two months later, the miss was back and it was still in adjustment. The rest of the engine was shot so I put in a junk yard engine, it turned out to be junk as well, but I got lucky on finding that reman 4AC on EBAY.

I still don't think that 5 deg BTDC will hurt anything as long as everything else is working properly.

I don't think adding a few extra degrees hurts either. Back in high school (67) I had a 57 Olds Super 88. It was a 2 door coupe with the short body and a 371 E2 engine. Back then, the J2 was the popular option engine for that car, few people heard of the E2, but it came with an isky cam from the factory. It was put on a dyno in the shop of one of the top Super Stock car owners at the time, the advance curve was optimized and the carb trim optimized. The initial advance was set to 4 deg more than the factory spec and you would not believe the difference that made in the cars performance.

Many a muscle car owner got a big surprise too when they couldn't keep up. Oh yeah, it also had a B&M kit in the hydro. It would jar your eyeballs every time it shifted, and chirped the tires, even on normal acceleration and on the downshifts when coasting to a stop.