gammalight
Cadet
- Joined
- Apr 13, 2009
- Messages
- 12
Hey all,
I have been troubleshooting the infamous Mercruiser 470 engine and am looking for some feedback and interpretations on my readings I am getting from my tests. The engine is on a 1986 19 foot Stingray.
The issue is when I am accelerating to WOT the engine begins to bog down at about 2000 - 2200 RPM. It bogs down so much the boat never reaches top speed. The engine starts right up on the first try and idles just fine around 700 RPM. It runs fine but once it hits around 2000 RPM or 8 mph it just bogs down.
The timing is set at 4 degrees tdc and the point gap is set to .0018 on a mallory distributor. The carb was rebuilt last year and I put a new fuel pump in as well. In the driveway the engine seems to run fine at 2600 RPM, I didnt run it too fast. Only under load does it start to bog down.
I did a compression test on the cylinders to see if I had a possible blown head gasket or cracked block. Although there was no water in the oil and the antifreeze level did not drop while I ran it. My readings are as follows:
#1 - 112
#2 - 100
#3 - 112
#4 - 112
Is this too low for a 470? They are all level across the board. Could I have a blown head gasket?
I warmed the engine up before I did it but did not have the throttle opened (not sure if this would change the readings that much). I also attempted a cylinder leak down test for the first time and for each cylinder I tested, set it at TDC. None of the cylinders lost any pressure.
Can anyone give me feedback on the compression test? I am not sure if the numbers are too low. I read a service anouncement that someone linked in a previous post that said they should all be 100+ psi.
Thank you so much! Have a great 4th of July!!
I have been troubleshooting the infamous Mercruiser 470 engine and am looking for some feedback and interpretations on my readings I am getting from my tests. The engine is on a 1986 19 foot Stingray.
The issue is when I am accelerating to WOT the engine begins to bog down at about 2000 - 2200 RPM. It bogs down so much the boat never reaches top speed. The engine starts right up on the first try and idles just fine around 700 RPM. It runs fine but once it hits around 2000 RPM or 8 mph it just bogs down.
The timing is set at 4 degrees tdc and the point gap is set to .0018 on a mallory distributor. The carb was rebuilt last year and I put a new fuel pump in as well. In the driveway the engine seems to run fine at 2600 RPM, I didnt run it too fast. Only under load does it start to bog down.
I did a compression test on the cylinders to see if I had a possible blown head gasket or cracked block. Although there was no water in the oil and the antifreeze level did not drop while I ran it. My readings are as follows:
#1 - 112
#2 - 100
#3 - 112
#4 - 112
Is this too low for a 470? They are all level across the board. Could I have a blown head gasket?
I warmed the engine up before I did it but did not have the throttle opened (not sure if this would change the readings that much). I also attempted a cylinder leak down test for the first time and for each cylinder I tested, set it at TDC. None of the cylinders lost any pressure.
Can anyone give me feedback on the compression test? I am not sure if the numbers are too low. I read a service anouncement that someone linked in a previous post that said they should all be 100+ psi.
Thank you so much! Have a great 4th of July!!