Oh boy, valve knock? Video inside

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Petros
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Re: Oh boy, valve knock? Video inside

Post by Petros »

it it was run out of oil it could be a number of issues, from connecting rod bearings to buggered cam shaft bearings. that one too sounds like top end, not so much rod knock. but hard to tell on a video.

the compression does not seem bad enough to be from pistons or rings, but that fouled spark plug looks suspicious, consider the other spark plugs look good.

I once had a valve guide come loose and make a tapping noise, also caused that one spark plug to foul since it was sucking oil in past the seal. the guide had bonded to the valve stem and was riding up and down in the head. compression was good, and ran okay but made tapping noise and was burning oil. I had to pull the head to fix it, they had to replace the guild and I replaced all the seals and exhaust valves.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)
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rer233
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Re: Oh boy, valve knock? Video inside

Post by rer233 »

Just had a look at some old engine parts I've got in my garage- there's a bolt (with a 14mm head) on the back of the camshaft that holds the distributor drive gear (which also is the excentric for the fuel pump lever) to the camshaft. Could that bolt be loose? Probably a long shot, but worth a try. Let us know!
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Re: Oh boy, valve knock? Video inside

Post by xirdneh »

Skirt may have fallen off piston #3 or 4 and is burning oil because cylinder is now scored. Or piston is cracked, but that usually does not cause loss of oil, and knocking quiets down when engine warms up.
Broken wrist pin will score cylinder too.
I have had all three happen. Skirt falling off has happened the most
Love those Tercell 4x4 wagons but they sure suffer from road noise.
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Neu
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Re: Oh boy, valve knock? Video inside

Post by Neu »

Alright, got the head off.

https://photos.app.goo.gl/2qmwWBd3wxHwAR1z7

I can't spot anywhere super obvious where the gasket would have failed. The cylinder walls all look and feel pretty great. There is a ton of carbon in 1 & 4 though.
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Re: Oh boy, valve knock? Video inside

Post by NWMO »

Were you getting pressure in the top end? It looks like significant oil being burned to me. Most likely either past the pistons or down the valve guides. The best looking piston/valves (for cleanliness), may be due to a head gasket leak or cracked head. If cylinder walls look good and pistons are within spec, you might get by with a re-ring. You do need to find the source of the noise as well.

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Petros
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Re: Oh boy, valve knock? Video inside

Post by Petros »

it is difficult to find a compromised head gasket by inspection. short of a section completely blowing out (you can tell when it runs on only 3 or even 2 cylinders), but a compromised head gasket can still run okay, and even have decent compression, but it seeps coolant into the cylinder. you can sometimes tell when you get chocolate milk looking oil (coolant in the oil reacts this way). or a clean piston crown, like you have in at least one cylinder in the photos. the piston top gets "steam cleaned".

You will want to remove the valves and carefully inspect all of the springs, rockers and valve guides for damage or excessive wear. new valve seals are in order, they do not cost much. I would also replace all the exhaust valves, and than lap in all of the valves seats if you are not going to have a machine shop regrind them (I do that often and it works fine if the seats are in decent shape). The exhaust valves get heat damaged in ways you can not tell, continue to driving on the heat damaged exhaust valves can lead to one breaking up, and often it will trash the whole engine. So it is worth the extra $30 or so for new exhaust valves. carefully inspect the cam shaft for pitting and excessive wear on both the cam lobes and the bearings, running low on oil, or with dirty oil, can cause excessive wear on the cam and running gear.

Also, as a precaution, I would replace the thermostat with a new good quality one (USA or Japanese brands). cheap ones give up early, or are often bad right out of the box, and not worth the risk to save $15-20 for the cheapo one made in a communist factory in the orient. Any questionable radiator and heater hoses should also be replaced. you do not want to damage the new head gasket, what ever caused it is likely still in the car.

Make sure you follow the head gasket repair guide I wrote up in the Repair guide section. it should ensure a more durable head gasket installation.

good luck.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)
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Neu
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Re: Oh boy, valve knock? Video inside

Post by Neu »

My main concern about putting it all back together is that the knock sounded pretty bad. It didn't sound like a head gasket to me but i could absolutely be wrong. I'm curious if I should pull the whole engine and start over. I can't really be sure. It turns over just fine by hand, I can't feel anything. I'll put more time into inspecting the head in a few days.

One thing I found interesting while I was pulling the head, several of the intake manifold gaskets were loose. Like I put my wrench on em and they turned without any force loose.

I'm replacing any parts I can get my hands on while I'm doing this, so things like thermostat, carb components, hoses, mounts, gaskets, etc.

My plan at the moment is to go buy that '83 in Longview, WA for $4k-ish and then rebuild this one. Then have two decent terdcels with the option to mod one. I'll definitely be removing that dash wood thing if I buy that Longview car.
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Petros
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Re: Oh boy, valve knock? Video inside

Post by Petros »

it is possible that the noise came from the pistons, I am not sure of any reliable test or inspection you can do with the head off, without removing the engine and pulling out each piston, and inspecting the connecting rod bears.

you might push down hard by hand on each piston in sequence when it is at TDC, and rotate the front pulley by hand. there should effectively be no slop or relative movement in the motion of the piston vs. the rotation of the front pulley. I would move the pulley back and forth while pushing down on the piston. The piston should move exactly with the crank rotation, no clunks or clicks, or gaps in motion. not you can tell if it is good, but if there is a big gap in the bearings, or the skirt is damaged allowing piston slap, you should be able to feel it.

I had a clacking sound once come from the valve train and found that one of the exhaust valve guilds had come loose in the head. it was bonded to the valve stem and was ridding up and down in the aluminum head just like it was the guild. it made some noise, but was still running, and seeping oil into the exhaust. I have also seen bad rocker arms cause knocking noises, and even broken valve springs make racket. so inspect all of the valve train components carefully.

Rod knock is usually a very solid sounding deep inside the engine hard clank sound, valve train damage will cause a lighter clanking sound high up on the engine. I have also had the piston skirt fail and it allowed the piston to rock back and forth about 15 degrees, it was still running, but smoked like crazy, and there was this hollow sounding "clump, clump, clump" sound. it did not sound like rock knock. but it was clear the engine had to come apart.

good luck.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)
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Neu
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Re: Oh boy, valve knock? Video inside

Post by Neu »

There's slop in cylinder 4 at the top of compression. No slop at the bottom.

https://photos.app.goo.gl/2bGFytnhcMUWXTfh6
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Petros
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Re: Oh boy, valve knock? Video inside

Post by Petros »

that much play usually means the cylinder bore is worn out oversized. you would get piston slap from it slopping around during combustion. I had that in the first Tercel4wd I bought, it did not last very long, the piston eventually broke apart. As I recall, it should only have like 0.006" of an inch clearance between piston and cylinder bore.

you either have to pull the engine to rebuild it. It should get oversized pistons and have a machine shop over bore it to exact clearance. And install new rings, and while you are at it new bearings and seals in the low end. Or you have to replace the whole engine with one in good condition.

On mine it only had 180,000 miles on it before the piston failed from too much wear and clearance. I suspect the previous owner had been running it without an air filter, or with dirty oil all the time, dust and grit wore out the bore.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)
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Neu
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Re: Oh boy, valve knock? Video inside

Post by Neu »

So that was likely the sound coming from the back of the engine. Makes sense.

So i'll likely look at over boring it and getting all the parts as i doubt i can find a spare engine. What's involved in that? Get the block machined, get the appropriately sized pistons and rings, anything else? It's likely a good idea to replace the bearings in the bottom end.
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Re: Oh boy, valve knock? Video inside

Post by Petros »

find a set of four oversized pistons. you can go either 0.020" or 0.040" oversized pistons, you must buy them first. they usually come with the correct oversized rings. you than take the stripped block with the pistons to the machine shop and they will match the bore to the piston dia. so you need the piston set first. you may have to search for an over sized set, last go around I went with 0.020" so I could one one size larger later if I needed to. After about 100k miles on our gravel roads I rebuilt the engine again, and went to 0.040" oversized. so if I make it last long enough, and get to do another rebuild on this engine I will have to locate another block since I am at the max over bore now on my engine. going the max oversize gives you a small amount more displacement, and slightly higher compression ratio. with care it should last 180k to 200k miles. I think driving on my dusty roads daily wore my bores out faster than normal, I should do more frequent oil changes. but you may have a hard time finding the 3ac over sized, the 4ac I have in mine I think is a more common engine. Ask around for the best local machine shop in your area, all the hot rod guys will know who is best. talk to them about procedures, services etc. some may want to use their own source of parts, which is just as well if they are a quality parts supplier (I recommend Japanese or usa made pistons only).

also bring the old pistons mounted on the connecting rods to the machine shop and they will press out the old wrist pins and install the rods on the new pistons for you.

likely the crank journals are okay, but you might pull the crank out and inspect the journals for wear and damage. if damaged you will have to have the journals ground and use oversized bearings. light lines on the journals can be polish out with strips of 800 grit wet and dry sand paper. To polish the journal, use soapy water or light solvent with the strip of sand paper wrapped around the journals, than wrap a cord around the journal and pull the cord back and fourth. it will give it nice even polish to the journal face. you can just than buy a set of standard size main and crank bearings, and front and rear seals, neither cost very much and are worth replacing.

good luck
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)
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