mercruiser 5.7 spark plug reading result

[bolo78910]

Re: mercruiser 5.7 spark plug reading result

This is a "new" motor right? Long block? Came with heads(new cam, lifters, guides, valves etc)? How many hours? Kind of funny about the EGR passage, as was previously stated shouldn't be on a marine engine. Was the intake changed?
The compression readings are a lot lower than I would expect (150-160) with a "new" engine. Are you checking the compression with a warm engine and the throttle wide open? The difference between # 8 and the other seven is not significant, but the generally low readings bother me.
Now, you said you adjusted the valves. Why? I'm a licensed auto tech and run a big car shop (wish it was marine), and providing the initial setup was done correctly valve adjustment is not normally required on a Chevy small block (same thing right?). Were you getting noise?
The correct adjustment is done with the engine off, zero valve lash plus specified number of turns ???. I don't have a Mercruiser spec, but 1/4 turn seems a little light, I would expect at least 1-1/4. Someone else in the forum can answer that.
Is the idle ok? What does a vacuum gauge show at idle and high idle? Steady at 16-18 (normal), regular downtick of 4 hg will indicate valve not opening correctly (worn cam or valve lash incorrect) or burnt valve. Rapid /vibration at higher rpm indicates weak valve springs. Fluctuating at idle but going away with higher rpm is valve guides.
Regarding the plug, I would be looking closely at a lean condition on #8. Pop the valve cover and check if the intake valve is opening. If its not could be a bent pushrod caused by improper valve adjustment or cam lobe worn off. Verify the exhaust valve as well.
If this looks ok go ahead and verify the valve adjustment. Considering the valve cover is off you might as well do all 8on that side. When I do this adjustment the engine is off as the manual states (But I'm a car guy). Try it running if you like, but it's not as exact and messy.
If all is well to this point, look at the intake manifold. A long block comes without an intake. Was the Intake checked & cleaned? Usually it has to be machined to match the new block. It could be the gasket is out of position. We use a plumbers propane torch with a small diameter vacuum hose attached, and with a low flow through the hose look for an rpm increase as it is passed over the suspect area. Not a good idea on an inboard so don't try it, but you can get the same effect by spraying a little bit of WD40 around the intake runner. If the idle jumps up or changes you've nailed it.

baileysboat thanks very interesting, yes it was a long block with heads , i install the old intake from the old block, i spray carb cleaner all over the intake gasket area with the engine running it did not make the engine runs different. about the egr port maybe i got it wrong so that is ok. it idle ok its a little coarse sounding shake just a tiny bit, now about the valve lash, Siam almost a hundred percent sure that these rockers need more tork, why because the way i got the engine the rocker nuts was screw down more on the bolts. if that is the case will that kill my compression?? because i know i should be getting at least 150 on all cylinders . so you are saying i should tork the rocker nut 1 1/4 from just where the rocker stop rattle??

if i found a bent pushrod on #8 is it easy to install another without pulling the head ? last what is the diffrent with adjusting the valve with the engine off the way the guys do it in the shop before the engine runs, and doing it with the engine running?? thanks

 

[bolo78910]

Re: mercruiser 5.7 spark plug reading result

000ps yes the engine was warm when i did the compression test also the trottle was wide open.

 

[drrm123]

Re: mercruiser 5.7 spark plug reading result

you said the firing order is different than whats on the boat how far off is it? only way to verify might be to pull valve covers and verify firing order by opening and closing of the valves. something else you can try is pulling off one plug wire and see how much rpm's drop should be about the same on each cylinder if working properly, only do this if its a boat with points ignition dont do on electronic ignition could blow module. if a pushrod is bent you just losen rocker arm and remove pushrod no need to remove heads. as for adjusting the valves their is no difference with either adjustment method just maybe a little messier. i normally give 1/4 to 1/2 full turn after clatter stops with engine running. and about 1/4 to 3/4 turn on new assembled engine cold on stand just want to preload lifter or you can even use a dial indicator .020 to .045 if you really want to be anal.

 

[bolo78910]

Re: mercruiser 5.7 spark plug reading result

you said the firing order is different than whats on the boat how far off is it? only way to verify might be to pull valve covers and verify firing order by opening and closing of the valves. something else you can try is pulling off one plug wire and see how much rpm's drop should be about the same on each cylinder if working properly, only do this if its a boat with points ignition dont do on electronic ignition cloud blow module.

drr thanks for saying that i just remember, i pull each spark plug wires and not even one cause the engine to stumble. with each plug pull one at a time the engine did not shake or miss, now that is weird. i pull the end that goes to the dist cap , but when i about to stick the wire back on the cal you can hear the tick tick tick spark and it shock as heck, your thought. oh boy i just see where you said it for points only oh well, i have electronic. well i just record a vidoe from youtube showing how to do the valvelash without the engine running, real nice so i will be back at the boat arm with info again thanks.

 

[drrm123]

Re: mercruiser 5.7 spark plug reading result

tick tick tick is normal if you pull wires pull them at the spark plug, be careful you can get zapped. just finished reading your post and saw the part about getting shocked, guess i was to late. if the valves are not ticking i would not mess with them. id check the timing to make sure correct, and that the firing order is right. why did you orginally adjust the valves? it's possible that some cylinders can run hotter than others, check manifolds to see if warmer in one spot than others when first starting engine, if you pull valve covers make sure pushrods are rotating. did someone break-in engine?

 

[bolo78910]

Re: mercruiser 5.7 spark plug reading result

yea the reason why i did mess with the valve is because i was getting a rattling sound, after lots of listen and trouble hoot , i bought a stetchope and found out it was the fuel pump, i change that and the knocking was history, right now the valve are not knocking, but my main concern is where is all my compression on a new rebuild engine, does the valve have anything to do with that?? i did break in the engine the right way i follow the manual and info from guys on here, about the firing order on the intake manifold, it is different from my firing order but i wire it the right way anyway. i am very much sure my firing order is wire correct, i went over it a million times .

 

[drrm123]

Re: mercruiser 5.7 spark plug reading result

If the valves are to tight on the #8 cylinder it could lose some pressure, by it coming up 20lbs after puttting oil in it, all others remained the same, you could have a problem. i'd still verify the firing order while your adjusting the valves too. should be 18436572 if rotor rotates clockwise. there is one that rotates counter clockwise thats different. compression ration of engine and piston design play part in how much cranking pressure you get too, if it's a low compression engine designed to run on 87 octane around about what your getting is close to normal. cylinders should be with in 10% of each other.

 

[John_S]

Re: mercruiser 5.7 spark plug reading result

Being an older boat does it have log type exhaust manifolds? ie risers are in the back, not in the center? If so, as what was stated earlier, you are probably getting a little water intrussion.

EGR block-off plate was probably what was stock. My 2brl manifold off the 5.7 Merc had it.

As far as firing order, tell us what is on the intake and how you have yours.

 

[bolo78910]

Re: mercruiser 5.7 spark plug reading result

If the valves are to tight on the #8 cylinder it could lose some pressure, by it coming up 20lbs after puttting oil in it, all others remained the same, you could have a problem. i'd still verify the firing order while your adjusting the valves too. should be 18436572 if rotor rotates clockwise. there is one that rotates counter clockwise thats different. compression ration of engine and piston design play part in how much cranking pressure you get too, if it's a low compression engine designed to run on 87 octane around about what your getting is close to normal. cylinders should be with in 10% of each other.

thanks again guys today i went back and the firing order is correct i look on another part of the intake and it read 18436572 i wire it clock wise, i re do the valves and i got the same compression reading as yesterday #8 is 130 also , but wait till you hear this, on my way home i took back the compression gauge to auto zone because it was a loner tool, the mangier look real closely on it and said they has gave me a guage that has problem it is not correct i was so **** i just walk out the store, when its rain it pour .any way i took it out for a test run using a stainless steel prop 15x17 mirage plus , water was like a lake, trim out real good this time, i am sure i did it right this time, wot was 3900 rpm at 25 miles per gps, only me on the boat with little gas in the tank, that not good, so what am looking at now is 15 x15 aluminum wich should put me about 4500 rpm at least , i think it realy need a 14 pitch but i think it is too small a pitch for a big boat.

?? been as how i has not reach max rpm for this fresh reman engine as yet, will the rings mess up because i take so long in getting it wot ? last what would i need to bolt a edelbrock on this intake, thanks.

 

[littlebookworm]

Re: mercruiser 5.7 spark plug reading result

I've been reading your posts and replies with great interest. Brooklyn was my home town. Anyway, you need a Mercruiser manual to properly set up the valve adjustment and the timing. It sounds to me that you have valves which aren't opening and closing properly. As to the edlbrock carb, you should get the matching intake manifold, making sure both are marine rated, not automotive. Keep in mind that if you are running in salt water with a raw-water cooled engine, which I seem to be, you should probably avoid the aluminum manifold because they do not hold up well - two different metals in a salt water system become a kind of battery causing galvanic destruction of the aluminum. good luck. Hy

 

[bolo78910]

Re: mercruiser 5.7 spark plug reading result

yea man you are correct something is not right, if i have the loot i would just give the job to someone with marine engine experience , these last few month is our favorite because tautog season if open, so i think i will just prop it with the 15 or 14 pitch, and finish the trouble shoot over the winter, i have to give the engine builder a call about the heads something is not right from day one , why the port side head is spewing oil from the pushrod like a pipe when engine is at idle, starboard side is so little oil i didnt even need to cover the head with cardboard when i adjust the valve, that cant be normal. and again with all these post about this engine some may think i am the one killing it lol thanks guys.

 

[drrm123]

Re: mercruiser 5.7 spark plug reading result

just trying to get as much info about what's going on, you said this was your first boat, did you run it before rebuilt engine was put in and how did it run? rpm max, mph, which prop was run? or why was engine changed? did mechanic you spoke with do a leak-down test? would give you more info than compression test. you mentioned changing manifolds is this a closed cooling system? also you can try changing plug from 8 cylinder with a different one then check again after running engine for a while to see if it burns differently. what was the dia & pitch on 4 blade prop? person from carver said not to rev past 4000rpm isnt that exactly where you were at. and 28 knots for a 5300lbs boat seen about normal to me. one last thing if bottom of boat has barnacles that will slow down your speed also.

 

[bolo78910]

Re: mercruiser 5.7 spark plug reading result

just trying to get as much info about what's going on, you said this was your first boat, did you run it before rebuilt engine was put in and how did it run? rpm max, mph, which prop was run? or why was engine changed? did mechanic you spoke with do a leak-down test? would give you more info than compression test. you mentioned changing manifolds is this a closed cooling system? also you can try changing plug from 8 cylinder with a different one then check again after running engine for a while to see if it burns differently. what was the dia & pitch on 4 blade prop? person from carver said not to rev past 4000rpm isnt that exactly where you were at. and 28 knots for a 5300lbs boat seen about normal to me. one last thing if bottom of boat has barnacles that will slow down your speed also.

ok here are some answers, first this is my second boat.
i bought the boat with a engine that was knocking i did not try to fix it even tho it start, why because it was sitting for 5 years . next the mechanic did not do a leak down test he just stated he had done the compression test.

next i re used the intake from the old engine.
it is raw water cool no close cooling system.
i just install new mr43t plugs a few day ago and it burn the same. manifolds and risers are new center stile no log stile.
diameter of the 4 blade i think it is a 15 x16 or 16x16 .
carver said with a 17 prop they was getting 4000 rpm, so i would be better of with a 15x15 prop
bottom of the boat is clean i pull it and re paint it about two weeks ago.

ok so that where we are, i am realy looking fro miracle with this old heavy boat i just wants to make sure the engine is running great, and i am getting the real w o t rpm.
mostly i have four guys on my boat when i go fishing, it is about 24 miles round trip to the reef, so i realy need to prop right for the extra weight.

thanks again guys

 

[littlebookworm]

Re: mercruiser 5.7 spark plug reading result

There are a number of things about how your engine is running that bothers me. You say it's spraying oil on one side and not the other when you try to adjust the valves with the engine running. That's not normal. Slight variation would be OK, but small blocks are known for spraying all over the place if you adjust valves with the engine running. The whole spark plug business is not right either. The valve adjustment is not right. You paid someone for a rebuilt engine. It should run like a new one once the adjustments are made. It's not doing so. I think you need to speak to the mechanic who rebuilt the engine and to the one who installed it. I think you should do it now rather than over the winter so that everything can be checked out and set up correctly. I wouldn't want you getting stuck with an engine that's not working correctly because of a mistake made by the rebuilder, who then blames you for "not doing something correctly." It's your money and your boat. You're entitled to get what you paid for. Get them to make it right. You might have to pay a little for the adjustments, but then you'll have peace of mind. Good luck and safe boating. Hy

 

[bolo78910]

Re: mercruiser 5.7 spark plug reading result

There are a number of things about how your engine is running that bothers me. You say it's spraying oil on one side and not the other when you try to adjust the valves with the engine running. That's not normal. Slight variation would be OK, but small blocks are known for spraying all over the place if you adjust valves with the engine running. The whole spark plug business is not right either. The valve adjustment is not right. You paid someone for a rebuilt engine. It should run like a new one once the adjustments are made. It's not doing so. I think you need to speak to the mechanic who rebuilt the engine and to the one who installed it. I think you should do it now rather than over the winter so that everything can be checked out and set up correctly. I wouldn't want you getting stuck with an engine that's not working correctly because of a mistake made by the re builder, who then blames you for "not doing something correctly." It's your money and your boat. You're entitled to get what you paid for. Get them to make it right. You might have to pay a little for the adjustments, but then you'll have peace of mind. Good luck and safe boating. Hy

well said buddy thanks, from day one i know something was not right, as i said one side of the head at idle oil is spraying all over the place, while one side barely pumping oil, i didn't even bother the cover that side with cardboard box to do the valves
i sent the builder an email today but he didn't get back to me as yet, so i will call him in the morning. i just got me a new mirage 15 pitch from ups , i will give it a test run . i will keep the update.

 

[bolo78910]

Re: mercruiser 5.7 spark plug reading result

up date on todays run, first i do as don s has told me to make sure i have a 1.5 gear ratio in the leg, i push the shifter in forward gear, i the turn the engine by the crank pulley bolt to take out the slop, i then put a mark on the pulley , the drive was already up so i know the slop was out. i turn the engine over by hand watching the mark on the pulley when it make one full turn, and half more turn the prop just make one full turn.

did i do that correct guys??? now i install a bran new merage plus 15x15 prop take it out for a spin, this is where it gets weird, trim wot only me on the boat i only manage the same 4000 rpm at 25 or 26 knots at the same 4000 rpm same rmp as the 17 pitch prop.

so now i am thinking maybe my tach is not working under load pass 4000 rpm.

next i barro the boat yard compression tester after going through about he gave a beatup looking one,

with engine warm up throttle plate wide open reading as followed,
# 1 120
# 8 120
# 4 140
# 3 120 was only 90 lbs when i hit valve with with a wood and mallet it goes up to the one 120
# 6 120
# 5 120
# 7 120
# 2 120

i hit all the rest of valve but they did not improve, the rebuilder told me to hit the valve, .. he also said the 120 compression is fine, he then ask me what i has the timing set at , i told him 8 degree, he laugh and said thats why you have no power, all his 350 engine sopose to set at 10 degree if it over heat a little i must back it down one degree. ha i am out of ideas here guys, what could cause changing from a 15x17 to 15x15 and rpm is the same,

is my tach

my coil

my carburator

my distributor

i am bout have enough, i am ready to ride it till if drop.

thanks please bear with my frustration i dont know which compression guage to belief. lol

 

[bolo78910]

Re: mercruiser 5.7 spark plug reading result

what happen i guess everyone gets bored with my long thread lol come on guys i just need some closing input, i know i have a lemon for a new reman engine, seller only say if i want he can replace the heads for me. i can dig that because the warranty is now up. just give me yall final input, because i am ready to ride it until it drop ,

just let me know why dropping from a 17 pitch to a 15 didnt improve my rpm by at least 400 .

is it my tach reading wrong

is it my coil

is it my carburetor

is it my distributor not advancing to the max

with these final answers i will put it to rest thanks.

 

[Maclin]

Re: mercruiser 5.7 spark plug reading result

The mallet thing sounds like a diagnostic "test". Having to do that in my view means that valvetrain adjustments are necessary.

Improper valve lash adjustment on the too-tight side will act like a rev limiter.

As far as initial ignition timing, 8 degrees versus 10 degrees does not sound like the problem especially since the prop change did nothing.

You can test the distributor advance easy enough with a timing light . A dial-back one is best for this. Run the engine up to 2400 rpm and use the dial-back light to get the timing mark to the zero line. The timing light's dial-back setting will be the total advance.

 

[MikDee]

Re: mercruiser 5.7 spark plug reading result

what happen i guess everyone gets bored with my long thread lol come on guys i just need some closing input, i know i have a lemon for a new reman engine, seller only say if i want he can replace the heads for me. i can dig that because the warranty is now up. just give me yall final input, because i am ready to ride it until it drop ,

just let me know why dropping from a 17 pitch to a 15 didnt improve my rpm by at least 400 .

is it my tach reading wrong

is it my coil

is it my carburetor

is it my distributor not advancing to the max


with these final answers i will put it to rest thanks.

IMO, 130 compression is usually what you get on a pretty worn engine, not a new, or reman. one! This could be the main problem?

You didn't gain any rpm because some thing is limiting your full power. Try Macklin's idea, and see if you're getting full spark advance by 2400rpm. An advance timing light is needed.

 

[bolo78910]

Re: mercruiser 5.7 spark plug reading result

maclin thanks , i realy think these heads are junks, i did the valve adjustment with the engine running loosen antil they start rattle, i then start tighten, as soon as it stop i give it just a half turn , before i gave them one turn , this time i only give it half because i dont want to make it too tight, just a test. and i get the same result, the valve train is not rattling it sound great. i dont have a advance timing light i have the other. when checking the advance is sopose to be in gear or nutral??

mikdee , you are correct how the hell a new engine sopose to only have 120 pis of compression the builder said maybe the rings are not seat as yet,

last what build compressions is it from the heads or the pistons??