Still Overheating!
11-17-2008, 07:13 PM
#31
Rennlist Member
cam timing causing overheating?? thats a big stretch. ignition timing, maybe, but not cam timing.
usually, if it is a slow coolant leak internally via the head gasket, it will show itself with the coolant analyser tester kit (about $40 at the autoparts store)
if that comes out good, then the next things to look at is the radiator. when it overheats, did you do as i said, and check the radiator? it should be blistering hot from top to bottom. any cool spots or sections is a flow problem, usually a water pump, air in the system non functioning t-stat, or clogged radiator.
checking flow when hot is tough. what I do is wedge a small electric gear from an electric motor, on to the t-stat to force it open, and then drive the car. if it still overheats, its not the t-stat, and is due to a flow issue. I also like to then disconnect the lower hose as it mounts to the t-stat housing, and put a garden hose up to the inlet near the t-stat by using a spare hose. (this way you dont have to disconnect the lower hose and re-attach it later) idling should require a little water from the garden hose. turn it up medium speed and start reving the engine. flow should increase with throttle and come out the lower hose which is now pointed into a bucket or with down on the ground.
This is a good way to see if you are getting flow through the system. But, you need to wedge the little splinned toy electric motor gear in the t-stat to do this test. the little gear is attached by pushing the movable t-stat part back until the shaft pulls out of its closed resting point. then, with the gear in place, the t-stat is forced to be wide open (about .5" gap showing) the t-stat is now in the hot position and will allow for normal flow. the only issue is that the car will take a little longer to warm up, but it will.
mk
usually, if it is a slow coolant leak internally via the head gasket, it will show itself with the coolant analyser tester kit (about $40 at the autoparts store)
if that comes out good, then the next things to look at is the radiator. when it overheats, did you do as i said, and check the radiator? it should be blistering hot from top to bottom. any cool spots or sections is a flow problem, usually a water pump, air in the system non functioning t-stat, or clogged radiator.
checking flow when hot is tough. what I do is wedge a small electric gear from an electric motor, on to the t-stat to force it open, and then drive the car. if it still overheats, its not the t-stat, and is due to a flow issue. I also like to then disconnect the lower hose as it mounts to the t-stat housing, and put a garden hose up to the inlet near the t-stat by using a spare hose. (this way you dont have to disconnect the lower hose and re-attach it later) idling should require a little water from the garden hose. turn it up medium speed and start reving the engine. flow should increase with throttle and come out the lower hose which is now pointed into a bucket or with down on the ground.
This is a good way to see if you are getting flow through the system. But, you need to wedge the little splinned toy electric motor gear in the t-stat to do this test. the little gear is attached by pushing the movable t-stat part back until the shaft pulls out of its closed resting point. then, with the gear in place, the t-stat is forced to be wide open (about .5" gap showing) the t-stat is now in the hot position and will allow for normal flow. the only issue is that the car will take a little longer to warm up, but it will.
mk
Fraggle,
Move back to Idaho where the weather's like in your avatar too much of the time and I suspect your overheating issue will go away..at least until late spring. Good luck. Keep us posted on what you find. There are a few 928s that seem to have persistent issues like this and the regularly know fixes just don't work. I still wonder about timing be a possibility but don't really know how to easily check it short of pulling the cam covers and doing the caliper thing. Mine checks out perfect with the PorKen tool but acts similar to your car.
H2
Move back to Idaho where the weather's like in your avatar too much of the time and I suspect your overheating issue will go away..at least until late spring. Good luck. Keep us posted on what you find. There are a few 928s that seem to have persistent issues like this and the regularly know fixes just don't work. I still wonder about timing be a possibility but don't really know how to easily check it short of pulling the cam covers and doing the caliper thing. Mine checks out perfect with the PorKen tool but acts similar to your car.
H2
11-22-2008, 10:15 AM
#32
Rennlist Member
Thread Starter
Think I found it... no longer in denial
Ran the compression test. Headgasket on the 1-2-3-4 side is toast.
#4: 174psi
#3: 95psi!
#2: 175psi
#1: 100psi
So it is off to "SEARCH IS MY FRIEND" to learn the best ways to pull this all apart. It is going to be a long winter!
Since I'll have it all apart, I'll probably go for new the new ford injectors, and anything else 'neat' I come across during my forum search. Eagleday is probably going to get a lot of business, a lot of my connectors are roasted.
I'm going to have to guess that pulling the heads is impossible with the motor in the car - it sure looks that way. I didn't really want to do anything this invasive until I got my lift, but I'm going to need the lift money to perform this rebuild!
I'll need to start building my parts list. This is going to be expensive. At least the mystery is over at this point. With the heads off I'll be able to make sure the water passages are all super clean as well.
I wonder how much space this car will take up when disassembled. My 914 is still down, too!
#4: 174psi
#3: 95psi!
#2: 175psi
#1: 100psi
So it is off to "SEARCH IS MY FRIEND" to learn the best ways to pull this all apart. It is going to be a long winter!
Since I'll have it all apart, I'll probably go for new the new ford injectors, and anything else 'neat' I come across during my forum search. Eagleday is probably going to get a lot of business, a lot of my connectors are roasted.
I'm going to have to guess that pulling the heads is impossible with the motor in the car - it sure looks that way. I didn't really want to do anything this invasive until I got my lift, but I'm going to need the lift money to perform this rebuild!
I'll need to start building my parts list. This is going to be expensive. At least the mystery is over at this point. With the heads off I'll be able to make sure the water passages are all super clean as well.
I wonder how much space this car will take up when disassembled. My 914 is still down, too!
11-22-2008, 12:08 PM
#33
Chronic Tool Dropper
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Since you have all winter, pull the motor and do everything all at once.
Space is always the final frontier. With the motor in a stand, the car can be rolled outside when you want to work on the motor, back in when you are finished for the day. Motor out is a slippery slope. There's a lot of cleaning and refitting needs that will tax your WYAIT capacity. But it will also be clean and nice when you are done. 20+ years of crud, goo, and aging on parts in there.
Space is always the final frontier. With the motor in a stand, the car can be rolled outside when you want to work on the motor, back in when you are finished for the day. Motor out is a slippery slope. There's a lot of cleaning and refitting needs that will tax your WYAIT capacity. But it will also be clean and nice when you are done. 20+ years of crud, goo, and aging on parts in there.
11-22-2008, 02:41 PM
#35
Rennlist Member
pull it. I did it n 2 weeks and built up a new motor during the process. you only need the lift for a few hours, or less. unbolt the exhaust, drop the clutch, yank the engine. Scot and I had his out and on a engine stand in a little over 3 hours. (and we are shade tree hacks) And, that was with headers too. if you dont have any , you can do it in less time. on a stand, you just unbolt stuff and can have the heads off in no time. new head gasket, check the heads for valve sealing at your local engine shop and put it all together. put on some new rings and bearings is a little longer process but kind fun. nice to not have to split the cases as the main bearings are probably fine. Then, you got a new engine!
mk
mk
11-22-2008, 08:48 PM
#36
Rennlist Member
Thread Starter
At this point I'm planning on pulling the motor. I'm in the hack league so we'll see how long it takes me and whomever I can grab for help to get the thing out. I'll drain and pull the rad tonight. It will be slow at the start, though.
I'm going to have to inventory all the bits and parts I'll need. I already have the valve cover gaskets, and some other bits, but I'll need to get a little of everything here!
I did a lot of WYAIT stuff on my first t-belt three years ago... then did the waterpump/tbelt again a month ago. Compression then wasn't nearly as bad, but it was borderline on the 1-2-3-4 side, running ~160 or so when the 5-6-7-8 side was 180+... I was hoping it wasn't this but I guess it is.
... and you know I can't put it back together stock....
I'm going to have to inventory all the bits and parts I'll need. I already have the valve cover gaskets, and some other bits, but I'll need to get a little of everything here!
I did a lot of WYAIT stuff on my first t-belt three years ago... then did the waterpump/tbelt again a month ago. Compression then wasn't nearly as bad, but it was borderline on the 1-2-3-4 side, running ~160 or so when the 5-6-7-8 side was 180+... I was hoping it wasn't this but I guess it is.
... and you know I can't put it back together stock....
11-22-2008, 09:21 PM
#37
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for what its worth...I had good results with a similar problem on an old 5 series bimmer using a head gasket sealer. $8 and 15 minutes labor and it cured the ailment. I ran the car another 2 years after without any mishaps.
11-22-2008, 09:29 PM
#38
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11-22-2008, 09:32 PM
#39
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Fraggle...
I can't remember if you checked radiator flow yet or not. I checked mine and thought it was fine...but just to eliminate that possibility, ordered and installed a brand new radiator...and it didn't make any difference. Both flowed about the same. Process of elimination here.
H2
I can't remember if you checked radiator flow yet or not. I checked mine and thought it was fine...but just to eliminate that possibility, ordered and installed a brand new radiator...and it didn't make any difference. Both flowed about the same. Process of elimination here.
H2
11-22-2008, 10:09 PM
#40
Rennlist Member
Thread Starter
I've got a brand new C&R in mine. New waterpump, new thermostat, the works. With the terrible compression test numbers, I'm headed in to replace everything. I've sourced a local guy who will let be "store" his spare engine stand for awhile.
Getting ready to pull off the hood, I've noticed that it has been done before.
There are alignment marks in pencil or pen around the mounts, just as I was going to put them. Interesting!
Getting ready to pull off the hood, I've noticed that it has been done before.
There are alignment marks in pencil or pen around the mounts, just as I was going to put them. Interesting!
11-22-2008, 10:34 PM
#41
Rennlist Member
similar overheating problem??? unlikely the stuff can work on a blown headgasket that is leaking combustion in the water jacket. outward, with water pressure can be stopped, but not the 1000+psi that is being forced out of the cylinder combustion chamber. I did all the head gasket leak products and it was a major pain to do it, but it was worth a try. after thinking about it, why would it work? it really cant. However, the small leakes in the headgasket that are outward, can be stopped and plugged with Barrs stop leak or similar products.
the low compression is a concern, and I think would have used the head gasket leak test kit before I broke things down. Then you KNOW!.
If you do have a head gasket leak and its over heating, usually this means the coolant system is over pressurized and you can be loosing water that way. If you are not loosing coolant, or overpresurizing the system, compression loss could be valves or rings.
mk
the low compression is a concern, and I think would have used the head gasket leak test kit before I broke things down. Then you KNOW!.
If you do have a head gasket leak and its over heating, usually this means the coolant system is over pressurized and you can be loosing water that way. If you are not loosing coolant, or overpresurizing the system, compression loss could be valves or rings.
mk
11-23-2008, 09:39 AM
#43
Rennlist Member
Thread Starter
Car is up on stands, need to pull off the undertray and start draining the coolant. Need to really clean my drain bucket so I can take a really close look at the coolant. At work today so I won't be getting to it until at least tomorrow.
11-23-2008, 10:14 AM
#44
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Fraggle...
I can't remember if you checked radiator flow yet or not. I checked mine and thought it was fine...but just to eliminate that possibility, ordered and installed a brand new radiator...and it didn't make any difference. Both flowed about the same. Process of elimination here.
H2
I can't remember if you checked radiator flow yet or not. I checked mine and thought it was fine...but just to eliminate that possibility, ordered and installed a brand new radiator...and it didn't make any difference. Both flowed about the same. Process of elimination here.
H2
Keep that up - and you can build another car out of spare parts.....
11-23-2008, 11:41 AM
#45
Team Owner
drain the block before you pull it, goodluck on your project