Blew a new head gasket?

Morgan44 · 10-22-2013, 07:32 PM

Hey fellas, I've made a few posts about my new to me 87 with the 244 2 stroke. I installed a new top end kit with great success. I then did the HEI mod from the sticky. I then blew a head gasket within the first 1/2 hour of it running again. Could the HEI cause this? Is I usually a overheating thing? I've replaced the head gasket and she's up and running again with the HEI. It seems to be running ok, but I haven't had a lot of run time. Im trying to decide why it happened and if I need to just remove the HEI and go back to the stock ignition. What do you think happened?

nobuckbuild · 10-22-2013, 09:21 PM

NO expert but it is possible , i would lean towards the ignition trigger being moved a little bit when you had the engine apart, that might have thrown off the timing enough to make it run hot, or to little fuel will also have the same effect , a just cleaned and built engine may not have the saturation of 2 stroke oil and gas causing the engine to run lean until you get to metal saturation causing it to heat up due to lean combustion or maybe you just got a bad gasket either way keep us posted

Morgan44 · 10-22-2013, 09:33 PM

Should there be some kind if "break in" period after a fresh build? Tonight I drive around about half throttle for 10 minutes or so to warm thing up somewhat slowly. When the gasket blew I was driving on a flat road wide open for maybe a 1/4 mile. I don't know, I Gus's I'm just trying to figure out if this ignition thing is good or bad. Is it really a better system than the stock? Or is it pushing things to the limit? I haven't had enough cart time to say wow, this really made a big difference. What was the original reason people started doing the HEI anyway?

Dave Box · 10-23-2013, 08:29 AM

There is no break in period as such, the pre 1980 manual just recommends that you run the first tank of fuel at 40:1 ( after 1980 the engine used an oil pump). If you blew a head gasket it is not going to be because of the HEI mod. It might be because

a) your head is warped, in which case it is about to blow again.
b) you did not torque the head down correctly (22 - 24 foot pounds)
c) you reused the old gasket ( I know you didn't)

The only reason to perform the HEI mod it to repair a defective ignition. The ignitor module from EZGO is ~$150, but it can be replaced with a Chevy unit for free, if you have one lying around, or $30 if you need to buy one. A lot of people take the opportunity to also replace the coil, wire and plug. Psychosomaticism being what it is, no matter how the cart performs it is much better than it used to be. This is the same placebo effect that you find when you change the drive belt to a shorter one.

Dave

Volt_Ampere · 10-23-2013, 09:42 AM

Blown new head gasket is usually caused by bad torque of the head bolts - warped head. Pull the head and check it for flatness. If it's flat, install new gasket and carefully torque it to spec (Use a torque wrench!) and use the correct torque sequence. Ignition change did not cause this.

Morgan44 · 10-23-2013, 12:04 PM

Ok, I follow you. So Dave, are you saying there are no performance gains to be had by changing to HEI, and switching to a shorter belt? Has anyone ever been able to determine some kind if operating temperature for these 2 stroke motors? In gonna shoot mine tonight and see where she is.

Dave Box · 10-23-2013, 01:06 PM

Well you might be gaining a bigger spark but seriously in a 1986 two stroke engine what would you hope to gain with that? IMO nadda the fuel in the cylinder is still going to burn.

I am one of those guys who did fit a shorter belt and yes in made a huge difference but then I stopped to think as to how it worked and came to the conclusion that it could not. The CVT belt is only gripped on the sides and that is where it wears. Once it is down to 1 1/16th it is going to slip and affect performance. Now the theory behind the shorter belt is that it fits tighter and delays upward shifting, but in fact the only improvement is that the belt is now 1 3/16ths again. The reality is that a short belt puts greater strain on the clutch bearings, the engine mounts and the starter motor. If you want greater torque at low speeds then the only way to do this is to fit a stiffer spring (or a big shim) in the driven clutch.

Of course other may disagree.

Dave

Morgan44 · 10-23-2013, 01:16 PM

I see what you mean on all points. This is the kind of info that makes forums great. Just so you know, up until last Friday I've never really looked or touched a golf cart below the seat. I enjoy the work of anything mechanical, or anything I can tinker with really. What about the temperature thing, have you ever looked into that? Thanks for the help.

Dave Box · 10-23-2013, 06:01 PM

Morgan, I am the same just love messing with mechanical things. If you every get (really) bored you could look at my blog to see how my 86 started life. As it happens the original coil, ignitor and pulsar are still running so my knowledge of the HEI mod is purely academic.
I have never monitored the engine temperature but as long as the fan is spinning and the fins are not clogged up you should be good.

Dave

dewzer · 10-23-2013, 06:14 PM

Not sure if this will apply in your case but head bolts come to mind. If they are bottomed out, the torque reading is not a true torque. I have seen some of the head bolts that require a flat washer/spacer so they dont bottom out.
Sometimes you never know what the last guy did.
Just thinking out loud.

10-22-2013, 07:32 PM	#1
Morgan44 Gone Wild Join Date: Oct 2013 Posts: 690	Blew a new head gasket? Hey fellas, I've made a few posts about my new to me 87 with the 244 2 stroke. I installed a new top end kit with great success. I then did the HEI mod from the sticky. I then blew a head gasket within the first 1/2 hour of it running again. Could the HEI cause this? Is I usually a overheating thing? I've replaced the head gasket and she's up and running again with the HEI. It seems to be running ok, but I haven't had a lot of run time. Im trying to decide why it happened and if I need to just remove the HEI and go back to the stock ignition. What do you think happened?
Morgan44 Gone Wild Join Date: Oct 2013 Posts: 690

10-22-2013, 09:21 PM	#2
nobuckbuild Gone Wild Join Date: Mar 2012 Location: CENTRAL PENNSYLVANIA Posts: 1,466	Re: Blew a new head gasket? NO expert but it is possible , i would lean towards the ignition trigger being moved a little bit when you had the engine apart, that might have thrown off the timing enough to make it run hot, or to little fuel will also have the same effect , a just cleaned and built engine may not have the saturation of 2 stroke oil and gas causing the engine to run lean until you get to metal saturation causing it to heat up due to lean combustion or maybe you just got a bad gasket either way keep us posted

10-22-2013, 09:33 PM	#3
Morgan44 Gone Wild Join Date: Oct 2013 Posts: 690	Re: Blew a new head gasket? Should there be some kind if "break in" period after a fresh build? Tonight I drive around about half throttle for 10 minutes or so to warm thing up somewhat slowly. When the gasket blew I was driving on a flat road wide open for maybe a 1/4 mile. I don't know, I Gus's I'm just trying to figure out if this ignition thing is good or bad. Is it really a better system than the stock? Or is it pushing things to the limit? I haven't had enough cart time to say wow, this really made a big difference. What was the original reason people started doing the HEI anyway?
Morgan44 Gone Wild Join Date: Oct 2013 Posts: 690

10-23-2013, 08:29 AM	#4
Dave Box Respect the Cart Join Date: May 2010 Location: Rocky Mount, Virginia Posts: 2,190	Re: Blew a new head gasket? There is no break in period as such, the pre 1980 manual just recommends that you run the first tank of fuel at 40:1 ( after 1980 the engine used an oil pump). If you blew a head gasket it is not going to be because of the HEI mod. It might be because a) your head is warped, in which case it is about to blow again. b) you did not torque the head down correctly (22 - 24 foot pounds) c) you reused the old gasket ( I know you didn't) The only reason to perform the HEI mod it to repair a defective ignition. The ignitor module from EZGO is ~$150, but it can be replaced with a Chevy unit for free, if you have one lying around, or $30 if you need to buy one. A lot of people take the opportunity to also replace the coil, wire and plug. Psychosomaticism being what it is, no matter how the cart performs it is much better than it used to be. This is the same placebo effect that you find when you change the drive belt to a shorter one. Dave

10-23-2013, 09:42 AM	#5
Volt_Ampere Gone Wild Join Date: May 2012 Location: Rio Verde, Az Posts: 7,170	Re: Blew a new head gasket? Blown new head gasket is usually caused by bad torque of the head bolts - warped head. Pull the head and check it for flatness. If it's flat, install new gasket and carefully torque it to spec (Use a torque wrench!) and use the correct torque sequence. Ignition change did not cause this.

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10-23-2013, 12:04 PM	#6
Morgan44 Gone Wild Join Date: Oct 2013 Posts: 690	Re: Blew a new head gasket? Ok, I follow you. So Dave, are you saying there are no performance gains to be had by changing to HEI, and switching to a shorter belt? Has anyone ever been able to determine some kind if operating temperature for these 2 stroke motors? In gonna shoot mine tonight and see where she is.
Morgan44 Gone Wild Join Date: Oct 2013 Posts: 690

10-23-2013, 01:06 PM	#7
Dave Box Respect the Cart Join Date: May 2010 Location: Rocky Mount, Virginia Posts: 2,190	Re: Blew a new head gasket? Well you might be gaining a bigger spark but seriously in a 1986 two stroke engine what would you hope to gain with that? IMO nadda the fuel in the cylinder is still going to burn. I am one of those guys who did fit a shorter belt and yes in made a huge difference but then I stopped to think as to how it worked and came to the conclusion that it could not. The CVT belt is only gripped on the sides and that is where it wears. Once it is down to 1 1/16th it is going to slip and affect performance. Now the theory behind the shorter belt is that it fits tighter and delays upward shifting, but in fact the only improvement is that the belt is now 1 3/16ths again. The reality is that a short belt puts greater strain on the clutch bearings, the engine mounts and the starter motor. If you want greater torque at low speeds then the only way to do this is to fit a stiffer spring (or a big shim) in the driven clutch. Of course other may disagree. Dave

10-23-2013, 01:16 PM	#8
Morgan44 Gone Wild Join Date: Oct 2013 Posts: 690	Re: Blew a new head gasket? I see what you mean on all points. This is the kind of info that makes forums great. Just so you know, up until last Friday I've never really looked or touched a golf cart below the seat. I enjoy the work of anything mechanical, or anything I can tinker with really. What about the temperature thing, have you ever looked into that? Thanks for the help.
Morgan44 Gone Wild Join Date: Oct 2013 Posts: 690

10-23-2013, 06:01 PM	#9
Dave Box Respect the Cart Join Date: May 2010 Location: Rocky Mount, Virginia Posts: 2,190	Re: Blew a new head gasket? Morgan, I am the same just love messing with mechanical things. If you every get (really) bored you could look at my blog to see how my 86 started life. As it happens the original coil, ignitor and pulsar are still running so my knowledge of the HEI mod is purely academic. I have never monitored the engine temperature but as long as the fan is spinning and the fins are not clogged up you should be good. Dave

10-23-2013, 06:14 PM	#10
dewzer Getting Wild Join Date: Jun 2013 Location: N.E. Michigan Posts: 126	Re: Blew a new head gasket? Not sure if this will apply in your case but head bolts come to mind. If they are bottomed out, the torque reading is not a true torque. I have seen some of the head bolts that require a flat washer/spacer so they dont bottom out. Sometimes you never know what the last guy did. Just thinking out loud.

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