Reply needed straight away

The fateful day awaits. That is tomorrow. My engine rebuild has been complete for a week now. I am so excited to get this thing turned over. I may have run into a problem, but maybe I'm paranoid and this is where I need some assistance. I ran a compression test to make sure things seemed right. Here are the results:

Cylinder 1: 170PSI dropped to 165PSI after a few minutes
Cylinder 3: 172PSI dropped to 171PSI after a few minutes
Cylinder 5: 105PSI held strong, 2nd reading: 126PSI held strong
Cylinder 2: 165PSI dropped to 160PSI after a few minutes
Cylinder 4: 160PSI dropped to 156PSI after a few minutes
Cylinder 6: 140PSI held strong after a few minutes

As you can see cylinders 5 and 6 or the transmission side of the engine have low levels. Cylinder 5 worries me a bit. This engine has gotten remanufactured heads with new valves, springs, seals, new head gaskets, new piston rings, new intake manifold and exhaust manifold gaskets, new main and rod bearings, you name it. Nothing has been seated yet. Does anyone think that the low PSI in Cylinder 5 is something I should be concerned with before turning this rebuilt engine over Sunday, or should I accept it as part of the seals not being completely set and go for it? Any and every bit of advice will be much appreciated. I don't want this engine to end up a dud. After 6 months and about $2,500 spent, this means a lot to me.

just to be clear, everything has been torqued, retorqued to specifications and triple checked. I made very sure before I moved onto the next rebuild step that it was all where it needed to be.

wtf? those specs are really disparate! double check? who built your engine?

Please explain what you mean Robo? I am the one who rebuilt my engine. I thought that was apparent.

One thing just for piece of mind. Try measuring it again. Make sure you get a good seal on the gauge, even though I'm sure you did to begin with.

I'll check it again in the morning. But I did check it twice. The first time I thought it had to be a fluke. I mean it held strong at 105 PSI the first time but I didn't think the seal was tight enough. The 2nd time I made sure it was sealed up good, but only gained about 20 PSI and again it held strong at that PSI for a good 5 minutes. Just not sure why it would be so low.

Been doing some research. Maybe It could be a valve not seating correctly. I could pop the front valve cover and make sure the rockers aren't pushing down too hard on the valves. I don't have adjustable valves or rockers, so it would be really simple. perhaps i could do a leak down test. put some oil in the cylinder and see is the pressure goes up at all. worth a shot. could let me know is the rings are causing it. Like I said the rings aren't seated to the cylinder walls yet.

Rings may not seal properly against the cylinder walls without a coating of oil. I understand your concern after all the work and money you put into this motor. Since the motor is already installed in the car, I would fire it up, let it run a bit, then recheck compression. At this point, if a problem exists in cylinder 5, it will need to be diagnosed and repaired, but a short break in may be all it needs. First, maybe pop off the front valve cover and check the rocker arm and push rod for a problem that may be keeping the valves from closing properly. Good luck. I'm pulling for ya!

X2, fire it up and break it in. Drive the car as soon as possible. Do a follow up check of cylinder pressure. If you find low cylinders, a leak down tester will reveal what is causing the low reading.

It could easily mean nothing more than that your rings aren't seated yet, which won't happen for a few hundred miles. Are you testing dry or wet? Dry testing can be more variable as well, especially considering the rings aren't seated.

If you aren't getting obvious leakage from somewhere, and are confident in the assembly and insertion of the rings, carry on.

Even a leakdown test doesn't mean much until it's been run for a bit.

I think if you had a bad problem, the cylinder pressure would be a quarter what you are seeing.

Thanks for the input guys. I checked the pressure with a lil oil in the cylinder and it went up about 5 PSI and when I popped the valve cover and retorqued the rocker bolts it shot up another 10 PSI. It matched the 6th cylinder now at 140 PSI.

Wolfmaster579 wrote:

Thanks for the input guys. I checked the pressure with a lil oil in the cylinder and it went up about 5 PSI and when I popped the valve cover and retorqued the rocker bolts it shot up another 10 PSI. It matched the 6th cylinder now at 140 PSI.

Great news, glad you found it. Did you fire it up?   

Unfortunately, I ran into an issue while pouring in the distilled water and antifreeze. Some of the RTV Sealant on the bottom of the water pump gasket must not of spread properly. It started to drip from the bottom bolt area. So I had to remove the water pump and re-seal it. Tomorrow I will be pouring in the water again. By then the RTV Sealant should be more then set. It only asks for 24 hours. I will check for leaks again and I'm shooting to try firing it up on Saturday.

I am seriously anxious to try turning it over sooner, but my wife isn't much help, I don't trust my brother and my friend isn't available until the weekend. I will keep all of you posted. I plan to video record when I get it runnin'. Hope I don't run into any other gasket seal leaks.

The story of everyone's life, "my wife isn't much help, I don't trust my brother and my friend isn't available until the weekend" haha

Fingers crossed for success on Saturday!

Does your motor have 3800 stamped on top or just the plastic cover??

James,
It has both a plastic cover that sits over the fuel injectors and fuel line, and it also has a 3800 stamped, painted red on the intake manifold.

His is 88, very first year of the official 3800. Same engine as in our 88 reatta.

That would be correct Evan the "VIN C" 3800. Wondering why James was curious about it, but eh..not that big a deal.

On another note, I finished the first gallon in the radiator and I can't get any more in at the moment. Guess I will have to wait until it cycles through the engine while it's running. No leaks that I can hear or see, so, water pump sealed.

And another note, the anxiety is KILLING me! Anybody close by that wants to help me turn this thing over? I DO NOT want to wait until Saturday. I'd say blame immediate gratification, but it has been 6 months of waiting really. Is this what it's like when you're waiting for your kid to be born? Just has to seem like the longest week in history!

I had an 88, 3800 motor with the stamp,best 1 ever had . Put 300.000 miles on it, still she would not die,tried 2 kill her daily.I think, taking out tstat made her invincible!!!

Wolfmaster579 wrote:

And another note, the anxiety is KILLING me! Anybody close by that wants to help me turn this thing over? I DO NOT want to wait until Saturday. I'd say blame immediate gratification, but it has been 6 months of waiting really. Is this what it's like when you're waiting for your kid to be born? Just has to seem like the longest week in history!

I wish I was closer. I love new engine startups. I assume you've been studying the different cam break-in techniques.

Derek,
I never removed the engine from the car. I tore down the engine down to the block while it stayed intact. So unfortunately, I could not remove the crank or the camshaft. I did several measurements to be sure they were in good shape and all the measurements led to standard bearings. They were both clean and smooth, so I didn't feel it was necessary to replace them either.

James,
I love my car so much. That's why I couldn't let the engine die on me. I had to rebuild it. The tapping was getting so loud and I was starting to slowly lose power. Once this engine is done and the wife and I save up sme money, I will getting the tranny rebuilt and some frame work down on the driverside front. I'm so excited to drive my car again. It's gonna be a totally different feel I think. Probably much better power, acceleration, gas mileage, etc. I fixed a lot of vacuum leaks, a few problematic gasket seal breaks, a missing timing chain dampener will certainly help, a deteriorating ignition control module, and more I can't think of right now. We'll see how it all works out. This engine only has abotu 190k on it right now. I'd love another 100k + if it feels like making it that far. Is removing the therostat that effective? I am curious about that.

Excellent. Startup should go easy enough if you don't have to worry about cam break-in.

I forget - that IS a roller cam engine, right? If so, even less to worry about!

Have you primed the oil pump? Not sure how to do that on a distributorless engine!

Derek,
Yes it is a Hydraulic Roller Tappet Camshaft. The oil pump gets primed by pumping oil up into the filter tube. Hopefully with the compression test being done and using dry cranking, the oil spread through the engine a bit.

The Buick, Pearl, she IS ALIIIIVVVVEEEE!!!!!! And She is ANGRY! God was she loud. My ears are still ringin'.

The ticking noise that I originally wanted to fix, I did not hear. Oil pressure was stable the whole time. Lots of smoking. Residual oil on the exhaust manifolds burning off and getting the oil out of the 5th Cylinder, That went away after about 5 minutes.

Gotta finish cycling the distilled water and antifreeze through the system, but that shouldn't be a problem. I tried to video the process, not like the camera could of handled the decible levels, but the camera shut itself off for some reason.

Now she can sit and cool for a while before I, check the fluid levels, retorque everything I can and start it up again. I am so happy right now.

I'd do the comp tests again after running it for a while for s's & g's just to see if it's any different you know
Really nice to see it's runnin! Why is it so loud though?

Yeah I will check out the compression again once i retorque it all and do the second running. It may have been loud because I was right over the engine and playing with the throttle to help seat the new piston rings. It is also sittin' in a garage, so I am sure that amplified the sound.

I hope my neighbor enjoyed it. I am sick of his 20 minute revving and tune fests on his 240SX every time he wants to take it for a spin.

Got an unusual oil pressure jump. It'll run around 49-55 steady for about 3 minutes, then it will shoot up to around 77-82 for a breif 5-10 seconds before dropping back down to it's previous pressure. I hope that isn't anything serious.

Everything has been retorqued and I found no leaks. I'm sure the oil has picked up some loose dirty bits being flushed out of the engine. So Next weekend I may give it an oil change and keep running it. I pulled the vacuum line off the throttle body and I can tell it is MUCH stronger, which I like.

It still idles a bit rough. Battery voltage drops into the 12v range and seems to make it idle that way. When the alternator is keeping the Volts around 13.5 to 14 it runs smooth, but that's only when it is running at higher RPMs. That is something it did before the rebuild.

Other then that, I am going to lift it back onto jacks and put it through the gears. Put some "no road miles" on it so to speak.