Engine Rebuild Noob need advice
10-27-2007, 04:58 PM
#1
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Thread Starter
Engine Rebuild Noob need advice
Hi everyone,
My 89 2.7 motor "done blowned up" at the Summit Point PCA Club Race a few weeks ago in a very spectactular fashion. I bought another 89 with 150K on the motor a week ago and I want to "freshien" up the motor and put it in my racecar while I disect the blown one later.
Now I've never rebuilt a motor before, but I'm not a total newby. I watched and helped others do a rebuild on a couple of 911 motors and I pulled my head last year for a blown head gasket. I've never pulled a 944 motor before but I don't expect that to create any great challenges.
However, my questions are related more to the actual rebuilding effort. I figure I can replace the rod bearings and various seals and items when the motors out and on the stand. Here's the meat of the question: where is the line in rebuilding where a generally compentent backyard mechanic stops and turns it over to a pro? Like when I did my head gasket, I didn't try to shave the head or replace the valves. I did all the monkey work of pulling it all apart, but when it was all out, I shipped it to the local machine shop where they replaced the 3 bent valves, shaved it a bit and gave it back to me a nice, clean and square. Well worth the money.
I'm sure there's folks out there who will say I can do it all myself, but that's not true. Experience does count for things. I don't want to find out that I didn't "do something" I should've while in there, or didn't recognize galling on the crack or something. I also don't have the next 6 months, maybe 3. And I don't want to buy a whole bunch of specialized tools that get used only once. I want to find that happy medium of time/money/skill. And I know it's impossible for everybody to know what that is for me, everybody's input will help me to narrow in on that medium.
Remember this is a race motor, it will spend a maximum of its lifetime at high rpms, not the occasional sprited blast in the mnts. So I'm willing to stop and hand it over to a pro when necessary, but I'm also willing to learn, try and save money. I don't want to just hand over the car to a shop and say "have at it" and get a 10K bill later. I'm a racer, any money I save by doing my own work will help go back into the tire/suspension/stuff happens fund. I want a reliable motor that develops good power, not a high hp grenade motor.
And here's another question while I'm thinking about it. We did a compression test on the new car and each cylinder was about 195-200. When I shot a squirt of oil down the cylinders, they jumped up to about 250-260. Does this mean the rings are worn and need to be replaced?
Thanks for everybody's help.
My 89 2.7 motor "done blowned up" at the Summit Point PCA Club Race a few weeks ago in a very spectactular fashion. I bought another 89 with 150K on the motor a week ago and I want to "freshien" up the motor and put it in my racecar while I disect the blown one later.
Now I've never rebuilt a motor before, but I'm not a total newby. I watched and helped others do a rebuild on a couple of 911 motors and I pulled my head last year for a blown head gasket. I've never pulled a 944 motor before but I don't expect that to create any great challenges.
However, my questions are related more to the actual rebuilding effort. I figure I can replace the rod bearings and various seals and items when the motors out and on the stand. Here's the meat of the question: where is the line in rebuilding where a generally compentent backyard mechanic stops and turns it over to a pro? Like when I did my head gasket, I didn't try to shave the head or replace the valves. I did all the monkey work of pulling it all apart, but when it was all out, I shipped it to the local machine shop where they replaced the 3 bent valves, shaved it a bit and gave it back to me a nice, clean and square. Well worth the money.
I'm sure there's folks out there who will say I can do it all myself, but that's not true. Experience does count for things. I don't want to find out that I didn't "do something" I should've while in there, or didn't recognize galling on the crack or something. I also don't have the next 6 months, maybe 3. And I don't want to buy a whole bunch of specialized tools that get used only once. I want to find that happy medium of time/money/skill. And I know it's impossible for everybody to know what that is for me, everybody's input will help me to narrow in on that medium.
Remember this is a race motor, it will spend a maximum of its lifetime at high rpms, not the occasional sprited blast in the mnts. So I'm willing to stop and hand it over to a pro when necessary, but I'm also willing to learn, try and save money. I don't want to just hand over the car to a shop and say "have at it" and get a 10K bill later. I'm a racer, any money I save by doing my own work will help go back into the tire/suspension/stuff happens fund. I want a reliable motor that develops good power, not a high hp grenade motor.
And here's another question while I'm thinking about it. We did a compression test on the new car and each cylinder was about 195-200. When I shot a squirt of oil down the cylinders, they jumped up to about 250-260. Does this mean the rings are worn and need to be replaced?
Thanks for everybody's help.
10-27-2007, 08:09 PM
#2
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I'm in the same boat, I'm planning on getting the bearings, the rings and taking it to a competent engine rebuilder and have them put the bottom end together, I'm afraid of getting the tolerances wrong. The rest I figure I can do myself, although I'll do the same with the head.
10-27-2007, 08:29 PM
#3
It sounds to me like you have the background to tackle this. Bolting together the lower end is do-able but make sure you follow the shop manual and use the correct sealant for bolting the 'girdle' back on. Cylinder bores are, of course, something you would have to farm out (and make sure the shop has done 944 engines). Even if they look good you should have them measured for taper, etc. If you install different pistons, the shop should hone to match the diameters. I would have a shop check the rods too. If you install the piston rings you will need a ring expander (and a ring compressor to get the pistons in).
10-27-2007, 08:34 PM
#4
Rennlist Member
I did mine with just my dad and other than the time it took it wasn't too bad. And I thought it was a fun way to pass a TON of time.
All I had was the Haines manual and my dad when I started.
You will need a gear puller for more than one thing, a flywheel lock, and I used a pickle fork to get the ball joints out. Oh, and a ring compressor to get the pistons back into the sleeves.... and snap ring pliers for the thermostat.
You will be able to take everything out and take it all apart by yourself, that part only takes time. (I didn't take the head apart at all, I left that to the machine shop). The head is the only part I never dug into. The shop told me I needed a couple new springs so I bought them and they put them in, and rebuilt everything that needed to be.
I sent my pistons, rods, crank and head all out to be cleaned and checked. And fixed. You also may have to have your cylinder walls taken care of. Mine were OK so I just left them alone.
We put everything together without much hassle, and a lot of Loctite 574.
My engine is dripping out of the damn lower balance shaft because I forgot to replace that frickin sleeve, so I'll be getting to that eventually.
Other than that everything is as good as I could ask for but I am one of those drivers that never puts the pedal more than 1/2 way down.
And BTW the whole ordeal cost me $3,334.16, and that includes wheel bearings, sensors, engine paint, header wrap, radiator hoses, vacuum hoses... and everything else I did while I was waiting for parts and machine shop.
That cost also includes a brand new TG#2 piston from Germany that ran me $415 shipped.
All I had was the Haines manual and my dad when I started.
You will need a gear puller for more than one thing, a flywheel lock, and I used a pickle fork to get the ball joints out. Oh, and a ring compressor to get the pistons back into the sleeves.... and snap ring pliers for the thermostat.
You will be able to take everything out and take it all apart by yourself, that part only takes time. (I didn't take the head apart at all, I left that to the machine shop). The head is the only part I never dug into. The shop told me I needed a couple new springs so I bought them and they put them in, and rebuilt everything that needed to be.
I sent my pistons, rods, crank and head all out to be cleaned and checked. And fixed. You also may have to have your cylinder walls taken care of. Mine were OK so I just left them alone.
We put everything together without much hassle, and a lot of Loctite 574.
My engine is dripping out of the damn lower balance shaft because I forgot to replace that frickin sleeve, so I'll be getting to that eventually.
Other than that everything is as good as I could ask for but I am one of those drivers that never puts the pedal more than 1/2 way down.
And BTW the whole ordeal cost me $3,334.16, and that includes wheel bearings, sensors, engine paint, header wrap, radiator hoses, vacuum hoses... and everything else I did while I was waiting for parts and machine shop.
That cost also includes a brand new TG#2 piston from Germany that ran me $415 shipped.
10-28-2007, 12:45 AM
#5
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.
And BTW the whole ordeal cost me $3,334.16, and that includes wheel bearings, sensors, engine paint, header wrap, radiator hoses, vacuum hoses... and everything else I did while I was waiting for parts and machine shop.
That cost also includes a brand new TG#2 piston from Germany that ran me $415 shipped.
And BTW the whole ordeal cost me $3,334.16, and that includes wheel bearings, sensors, engine paint, header wrap, radiator hoses, vacuum hoses... and everything else I did while I was waiting for parts and machine shop.
That cost also includes a brand new TG#2 piston from Germany that ran me $415 shipped.
10-28-2007, 03:04 AM
#6
Rennlist Member
Well... a lot of bad things happened to my engine, and a lot of random things got replaced.
Which is what I was saying, it shouldn't come out to be anywhere near what I spent during that 6 months.
Which is what I was saying, it shouldn't come out to be anywhere near what I spent during that 6 months.
10-28-2007, 11:50 AM
#7
Rennlist Member
I never re-built a car engine before, but decided to try it on my 83. I let the machine shop check the tolerances on the crank, magnaflux, and polish it. They also did all the head work. The rest I did myself. I just followed the factory manual for the rebuild, and took my time, and was very meticulous at each step. Now at 21K miles later, it is still running great with no leaks. I even had it on the track this summer and it survived the red line full throttle runs all day.
About the only thing I did special was use forged rods and the Lindsey oil baffle kit. Everything else was stock. Because I want to run 944 spec one day.
I would say unless you are going for something wild in your rebuild, and going to exotic rpm limits, you should be able to handle it yourself. It's not that difficult, and you should be able to do it in 3 months time if you have all the parts. You'll need the standard 944 tools for the belt stuff and good accurate torque wrench. And a couple of the engine rebuild items as mentioned.
Have fun!
About the only thing I did special was use forged rods and the Lindsey oil baffle kit. Everything else was stock. Because I want to run 944 spec one day.
I would say unless you are going for something wild in your rebuild, and going to exotic rpm limits, you should be able to handle it yourself. It's not that difficult, and you should be able to do it in 3 months time if you have all the parts. You'll need the standard 944 tools for the belt stuff and good accurate torque wrench. And a couple of the engine rebuild items as mentioned.
Have fun!
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10-29-2007, 07:51 AM
#8
Pro
Thread Starter
Thanks guys for all the answers. The journey has started. We pulled the motor yesterday with the only real problem was a very rusted and stuck steering knuckle. We wasted a huge amount of time on it and ended up removing the top knuckle which was slightly less rusted. We ran out of time and didn't get it on the engine stand because we could get the bell housing off but that's ok. The next order of business is up on the stand and then a huge dousing of engine cleaner. Man that engine is filthy. I even found peanut shells on the top of it. It really made me appreciate how nice it is to work on my race car where things are clean, anti-seize applied, etc. It's a shame how some people treat their cars.
10-29-2007, 11:38 AM
#9
Race Director
I rebuilt my 944 spec motor at home.
In fact I have done 3 motors.
1. Put the motor in a stand at tear it all down. Clean all the parts.
2. Send head to machine shop for ensuring flatness and vavle seating. For a spec car a stock valve job is all that is needed
3. Get top and bottom end rebuilt gasket sets
4. get new rod and main bearings. standard size is most common. you could try to measure or take the crank to a shop and have them inspect. Probaly good to have them cross drill
5. Rings - I have had good experience not installing new rings. I did put in new rings on my latest spare motor. I never touched the bores
6. With clearn parts re-assemble to factory specs using the factory manual.
Now this sort of job would get you a mid 130 whp 2.5L motor. I am not sure what it would do for a 2.7L, but probably the same plus a few hp.
Cost will be about $1000 to $1600 depending on cost for head & crank work and incidentals.
In fact I have done 3 motors.
1. Put the motor in a stand at tear it all down. Clean all the parts.
2. Send head to machine shop for ensuring flatness and vavle seating. For a spec car a stock valve job is all that is needed
3. Get top and bottom end rebuilt gasket sets
4. get new rod and main bearings. standard size is most common. you could try to measure or take the crank to a shop and have them inspect. Probaly good to have them cross drill
5. Rings - I have had good experience not installing new rings. I did put in new rings on my latest spare motor. I never touched the bores
6. With clearn parts re-assemble to factory specs using the factory manual.
Now this sort of job would get you a mid 130 whp 2.5L motor. I am not sure what it would do for a 2.7L, but probably the same plus a few hp.
Cost will be about $1000 to $1600 depending on cost for head & crank work and incidentals.
10-29-2007, 11:41 AM
#10
Race Director
944 spec does not allow anything other than stock rods from the 83-88 944 NA. The oil pan baffle is legal and many cars run them, but non-stock rods are not.
10-29-2007, 01:55 PM
#12
Race Director
They they are stock and subject to the update/backdate rules which therefore allow them. The prior post mentioned the only things non-stock and in that statement mentioned the oil pan baffle and forged rods. Aftermarket or 951 Forged rods are not legal in any 944 spec car. The only way these parts are legal is that if they came from the factory in any one of the US spec 83-88 944 NA 2.5L 8valve motors. Parts unique to other model years or engine types are not legal in the class even if they are factory. The exeptions to that are clearly noted in the rules and are considered allowable modifications.
10-29-2007, 10:28 PM
#14
Rainman
Rennlist Member
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You've worked on 911s? Pulling an engine should be second nature then 
I managed a full rebuild in my garage on a rented engine stand. There will be a few of those "one time use " tools but they aren't very expensive so it's ok. The only work I had someone else do was having a machinist cut off .0020" off my head because it was pitted, and shaving paint off the painted letters on my valve cover. Other than that a good chemical spray was all it took.
I managed a full rebuild in my garage on a rented engine stand. There will be a few of those "one time use " tools but they aren't very expensive so it's ok. The only work I had someone else do was having a machinist cut off .0020" off my head because it was pitted, and shaving paint off the painted letters on my valve cover. Other than that a good chemical spray was all it took.
