How to get top dead center on 86 merc 170?

[jake1z]

Redoing my head gasket. I want to get the engine to tdc before i bolt the head on to aid with the rocker arm installation. on a mustang i know its when the number 1 piston is at its highest point, is it the same for the merc 170 4cyl? I cant find it in the manual. Thanks

 

[stonyloam]

Re: How to get top dead center on 86 merc 170?

TDC is #1 at the top of its (firing) stroke, with both valves closed. rotor in distributor should be pointing toward #1 wire.

 

[salty3rd]

Re: How to get top dead center on 86 merc 170?

Thier also should be a line on the harmonic balancer, when that is lined up with the timing marks on the engine, #1 is at TDC.

 

[jake1z]

Re: How to get top dead center on 86 merc 170?

thanks guys

 

[jake1z]

Re: How to get top dead center on 86 merc 170?

finally getting around to doing this but now the engine wont turn over by the bolt on the crank. do i have to remove the front pulley or some thing? i turn the bolt the the engine doesnt move i dont want to turn it any more in fear of it snapping off.

 

[stonyloam]

Re: How to get top dead center on 86 merc 170?

Don't blame you. There are three threaded holes in the front of the balancer, I think they are 3/8-16. You could thread long bolts in there and use a bar against them to turn it over.

 

[Todd157k]

Re: How to get top dead center on 86 merc 170?

If your heads aren't on, and you can't turn the motor somewhat easily, you've got a serious problem.

 

[Don S]

Re: How to get top dead center on 86 merc 170?

If your heads aren't on, and you can't turn the motor somewhat easily, you've got a serious problem.

It's not hard to do at all. All you need is an OEM service manual and the ability to read and comprehend what you are reading and it's very easy to do.
It also helps to know how many times the cam turns as compared to the crankshaft, and what the 4 strokes of a 4 stroke engine are, and what the valves are doing. Once you figure that out, it's sooooo easy to get #1 TDC on the compression stroke.

 

[jake1z]

Re: How to get top dead center on 86 merc 170?

on my mustang i turned the engine by hand with my finger on the number 1 cylinder until i felt air pushing out. once the balancer said tdc after that it was good to go... my biggest problem right now is its not spinning and i already torqued the head, intake, and exhaust manifolds on... i need to get tdc to torque the valve springs

 

[Todd157k]

Re: How to get top dead center on 86 merc 170?

You may have the timing gears off or the cam and you're banging a piston into a valve. Don't force it.

 

[jake1z]

Re: How to get top dead center on 86 merc 170?

i couldnt turn it even when the head was off... the motor goes clock wise right

 

[Eric 3.7LX Alpha 1]

Re: How to get top dead center on 86 merc 170?

on my mustang i turned the engine by hand with my finger on the number 1 cylinder until i felt air pushing out. once the balancer said tdc after that it was good to go... my biggest problem right now is its not spinning and i already torqued the head, intake, and exhaust manifolds on... i need to get tdc to torque the valve springs

Same thing on the boat.
Is the outdrive in gear, maybe tough because of that. I think I would pull the outdrive off the boat,(while in forward), and see if it is still not turning. It should not be that hard with the plugs out, heads off, same difference. Should turn over like butter, without any compression resistance. So what else can be giving resistance? a bearing? How did the cylinder walls look? Any damage?

Timing chain being not aligned is not the problem because you don't even have the rockers on the head yet, so the camshaft lobes aren't opening the valves yet.

 

[jake1z]

Re: How to get top dead center on 86 merc 170?

i just tried it again nothing... i put the boat on craigslist for 2k i just bought the thing for 3200 and dumped another 4 into it... i hope the guy who sold it to me rots in hell...

 

[jake1z]

Re: How to get top dead center on 86 merc 170?

the starter wont turn the motor either.... could the starter be jammed? the motor cranked fine before i pulled it all apart, i turn the key and the volt gauge goes up, i can raise and lower the trim but the started doesnt make a sound and when i try to start it.

 

[stonyloam]

Re: How to get top dead center on 86 merc 170?

the starter wont turn the motor either.... could the starter be jammed? the motor cranked fine before i pulled it all apart, i turn the key and the volt gauge goes up, i can raise and lower the trim but the started doesnt make a sound and when i try to start it.

No click ?? Nothing?? Then it is probably not the starter, because if it were you would hear the solenoids (slave and starter clicking).Find the slave solenoid (on side of block) and jumper from the red/purple wire on top to the small yellow/red wire on front. Solenoid should click and starter turn, if not jumper from r/p to large y/r wire (bypass the slave solenoid), starter should turn, at least click. It can be pretty frustrating, hang in there.

 

[jake1z]

Re: How to get top dead center on 86 merc 170?

the jumping wires hting didnt work... had my car hooked up tp the battery too so it has plenty of juice... maybe a missing ground wire or some thing... doesnt make a sound when the key is turned. ive looked over the engine a 100 times and cant find any wires that are not connected.. does the ground wire on the carb have anything to do with it.

 

[stonyloam]

Re: How to get top dead center on 86 merc 170?

Your circuit breaker may have tripped. Should be a red button to reset it. You should have +12 volts on the R/P wire on the slave solenoid. If not You may have a bad system ground (battery cable) or the breaker. If you jumper from the + battery terminal to the large y/r wire on the slave, and you still get nothing, most likely a bad ground. instruments, lights work? Try removing the ground battery cable, cleaning and tightening it (where it attaches to the block). Good luck.

 

[T-Max]

Re: How to get top dead center on 86 merc 170?

It's not hard to do at all. All you need is an OEM service manual and the ability to read and comprehend what you are reading and it's very easy to do.
It also helps to know how many times the cam turns as compared to the crankshaft, and what the 4 strokes of a 4 stroke engine are, and what the valves are doing. Once you figure that out, it's sooooo easy to get #1 TDC on the compression stroke.

Translation: You appear to be out of your depth here.

I think I have to agree with Don on this one. Particularly when you say you "need to get tdc to torque the valve springs." Why do you say that? Why do you think you need to get to TDC at all?

This engine has hydraulic valve lifters so there's no valve adjustment involved. I'm not aware of any reason an engine should be at TDC on any cylinder when re-installing the head, but if that's the case, feel free to enlighten me.

As far as helpful advice, as opposed to just pot-shot criticism of your mechanical talents, I note that you said "the motor cranked fine before i pulled it all apart." So the first question I'd ask is:

1) How long ago was that?

In other words, how long a period of time did the boat sit around after it "cranked fine" and until you pulled it apart? You may have had some water get into the engine during the interim which caused the engine to get stuck.

Which leads me to my second question:

2) How did the cylinders look when you had the head off? Any indication of rust? If so, it might just be "stuck" (like my 170 was -- see my thread on that)

It's too bad that you put the head back on before confirming that the engine would turn rather freely when you had the head off. Even with the head back on it should turn freely as long as the spark plugs are out. Any compression will just come out the spark plug holes.

You either have a stuck engine or a stuck outdrive that's preventing it from turning. Try answering my questions and maybe we can figure it out. But frankly, I'm thinking you might well have to pull the head back off, unless it's just a stuck outdrive that's the problem.

 

[stonyloam]

Re: How to get top dead center on 86 merc 170?

Particularly when you say you "need to get tdc to torque the valve springs." Why do you say that? Why do you think you need to get to TDC at all?

This engine has hydraulic valve lifters so there's no valve adjustment involved. I'm not aware of any reason an engine should be at TDC on any cylinder when re-installing the head, but if that's the case, feel free to enlighten me.

On the 470 engine you must torque the rocker arm nuts with the valves closed. So you need to be at TDC to do part of them and turn the engine 360 degrees at the crank to do the rest.

 

[T-Max]

Re: How to get top dead center on 86 merc 170?

On the 470 engine you must torque the rocker arm nuts with the valves closed. So you need to be at TDC to do part of them and turn the engine 360 degrees at the crank to do the rest.

Ahhhhhhhhhhhh, so. Thanks for that info, especially since I will be re-installing my head and rockers one of these days. I assume that this info is in the manual? (I haven't looked at it yet)

That makes for an interesting procedure. I'll see what the manual says on it but it looks to me like you'd start at power-stroke TDC on #1 (as Jake says) and torque those rockers. Then rotate clockwise (vis-a-vis the front pully/hub) 180 degrees and do the rockers on #3 (firing order 1-3-4-2) , then another 180 degrees and do the rockers on #4, then another 180 degrees and do the rockers on #2, and yer done. having the pushrods in place for each of the next cylinder(s) (3,4,2) should confirm that they are both "down" before you torque the rockers for that cylinder.

I think I have that all right, but please correct me if I'm wrong.

I guess the thinking on that is that if you torque a rocker arm with the lifter in the up position, you might just bend the pushrod. I can't think of any other reason for requiring that the lifters be down when torquing the rocker arms, except maybe affecting the torque reading (which just might be the reason).

I guess it's been too long since I did a valve job or head replacement on an engine with hydraulic lifters.

Speaking of which, I need a pair of new lifters on my engine. I wonder if they are just standard Ford 460 lifters (like the head is)? Just curious since I found a supplier for the Mercruiser lifter at something like 8 bucks, which is very reasonable (might even be cheaper than the Ford dealer's price).

I've also read that I should def go with the Mercruiser head gasket. Do you have any opinion on that, Terry? I find your posts very informative and knowledgable (and thus helpful), unlike some folks here who just seem to be happy taking a shot -- like they know it all (which they clearly don't) -- as opposed to providing helpful info.

But, to each his own, I guess. Still, it looks to me like most of the "shots" I've read are basically incorrect, misleading and, frankly, pretty lame. I came on here for help from knowledgable folks willing to share, not to be the target of some troll looking to take a cheap shot in some misguided attempt to appear superior -- and then basically making an arse out of himself to anybody who really does know what's goin' on.

But, I guess whatever floats yer boat, huh?

Pun intended.

So much for THAT tirade!!!!! End of Rant!