Have to rebuild my engine, WHAT SHOULD I DO TO IT?

JABM · 02-24-2002, 11:05 AM

Well, my new porsche needs a new engine.
I was at the mechanic's the other day and we found oil in the intake tract; boost tubes, intercooler, intake manifold, everything. We also think there was some oil in the coolant. So now that I need new rings and a new head gasket, I figure I might as well build the engine. My post is intended to get advice on how to go about doing this.
I already paln to port and polish the head and intake, and do a wide fire gasket. I was thinging about boreing the blcok to a 2.7 liter and maybe getting a garrett t4 turbo. Any thoughts? All suggestions as to what to do are welcome. I am going to be pulling the engine myself and do the work I can maylsef also. (Clearly I will send out the head and intake for port and polish).
Jordan

arnebret · 02-24-2002, 11:33 AM

A bit of oil in the intercooler pipes and intake manifold is not that big a trouble... Some oil can always come in, especially with the turbo. Because you will only be opening the intake parts once a year o so, quite a bit of oil can be found there. If it's excessive you may have a leak somewhere. But if you discovered oil in the coolant and found other evidence that forces you to do engine job, just do it. It can be a long process, but it's worth the money and time.

Lawrence Coppari · 02-24-2002, 12:32 PM

How do you know you need new rings?

I believe you can get 2.7 liters with just a crank change.

Except for for the oil in the water, your only problem might be a turbo seal.

A little oil in the intake is pretty much the norm.

JABM · 02-24-2002, 12:52 PM

all the boost hoses, intercooler, and intake manifold had oil, when we pushed the manifold butterfly valve open, oil spilled out too. My mechanic and I both thought this oil came from blow by due to bad piston rings, if this isnt the case, how can I tell for sure?

Lawrence Coppari · 02-24-2002, 02:06 PM

Seems to me that if the rings were that bad, the engine would smoke a lot. What you describe is indeed too much oil in the intake. How would oil travel from the cylinder to the intake? The intake valves are always shut when the pistons come up. My feeling is that the oil is coming from the turbo.

Do a compression check. That'll tell you something about the rings and valves.

Before you do a complete rebuild, I'd replace the turbo first. That might cure your oil in the intake problem. You've lost nothing by only replacing the turbo because you were planning on doing that anyway.

JABM · 02-24-2002, 04:46 PM

Supposedly the turbo was recently rebuilt by turbonetics and I think fitted with the #8 compressor housing. So I would think that it would be fine. The engine does smoke a little bit after driving for a while, however I had thought that I had a leak in an oil line and that the smoke was coming from the oil cooking on the outside of my engine. I am doing a compression test tomorrow to see if the culprit is bad rings or a bad turbo seal. Could it possibly be a bad crank case bleaders as well?

If I do an engine rebuild, I was thinking about getting Huntley Racing to do a long block for me, has anyone had this done? Any advice? I was curious about whether Speed Force Racing might be a better way to go.

Jordan

Lawrence Coppari · 02-25-2002, 03:28 AM

I may be missing something but I don't see how oil can get upstream of the intercooler unless it comes from the turbo. Someone needs to explain this to me.

Mine would smoke externally also. Got so bad that it would let out a belch from under the car after a hard turn on the track. This was caused by my procrastinating about replacing the oil pan gasket and allowing it to get worse and worse. I finished the job along with rod bearings two weeks ago. It is dry now and no more belching of smoke because there is no more leaking oil collecting in the drip pan then spilling onto the crossover pipe.

The oil leak was such that if I got a certain light red in the morning on the way to work, burning oil fumes from the crossover pipe would rise to the engine compartment and be picked up by the blower and pushed into the car - nothing like the smell of burning oil first thing in the morning. It reminded me of what Robert Duval said in "Apocalypse Now" regarding napalm.

Keep us posted on what you find with the compression test.

arnebret · 02-25-2002, 10:11 AM

I have to agree with Lawrence. Oil in the intake track can only come in by the turbo (or your filter->turbo pipe is leaking and sucked up oil somehow)... Normally a little bit of oil leaks in the turbo, we are talking LITTLE bits here.. but if oil is flowing out of the intake manifold after open the throttle plate it seems your turbo was doing work as an oil pump or something else was terribly wrong in the engine...

JABM · 02-25-2002, 02:44 PM

Did a compression test today.
#1 - 130 psi
#2 - 135 psi
#3 - 135 psi
#4 - 135 psi

We poured a little oil into #1 and tested again, getting 145 psi, so some compression is leaking past the piston rings. Do you guys think that this is still within acceptable limits?

Also, the oil can get into the intake through the crankcase breather. If pressure coming through the rings from the cylinders goes into the crank case, it has to escape somewhere. It will go through the crankcase breather and in doing so push oil through which will travel up and into the intake.

JABM · 02-25-2002, 02:49 PM

I am getting a leakdown test done in a few weeks to see where exactally I am losing compression from.
How can I tell for sure if my seal on my turbo is blown or leaking? My mechanic doesn't do a lot with turbo cars and wasn't sure how we could tell.
Jordan

Mrmerlin · 02-25-2002, 04:54 PM

Hi JABM, to check the turbo, it requires about an hour , you will need to remove the aircleaner and get to the intake pipe for the turbo when you see the turbo,spin the impeller, see if it rotates smoothly, (your looking for any dicernable notches)if so good, also try to wiggle it from side to side to check for play if it has some then this is a good indicator that your turbo needs a replacement bearing installed, this loose bearing will let oil leak into the the exhaust tubine side.
Or the intake compressor side (sounds like this is already happening).
The compression results sound about right remember that you have a turbo so you wont find 160psi cyl s as the turbo runs a lower compression piston, these #s are about what I have in my car give or take 5psi......Stan

Britwrench · 02-25-2002, 06:19 PM

Do a leak-down test and check the results. Also, the compression test has to be done with the engine at normal temperature and the throttle wide open. (Remove the DME relay when cranking the engine). The gauge should show about 75% of the final reading first crank.

Lawrence Coppari · 03:10 AM

The Porsche manual provides both axial and radial runout for the turbo. Your compression sounds fine to me. These engines are low compression. Five pounds difference is not much.

garrity928 · 03-10-2002, 04:54 AM

The turbo definitely passes oil no matter what you do it seems. The other way to get oil into the intake tract is through crankcase vetilation problems. When the engine runs high vaccum, the oil can often be sucked out of the engine, and into the intake. I wouldn't worry about the oil in the intak tract, only if it starts blowing a lot of smoke. Just clean the oil out of the intercooler with some gasoline or solvent.

Garrity

porscheboi928s/c944t/n · 04-12-2002, 05:45 AM

The other way to get oil into the intake tract is through crankcase vetilation problems. When the engine runs high vaccum, the oil can often be sucked out of the engine, and into the intake. I wouldn't worry about the oil in the intak tract, only if it starts blowing a lot of smoke. Just clean the oil out of the intercooler with some gasoline or solvent.

Garrity
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that is how i see ur problem with ur car..........

geoffbaltz · geoffbaltz's Garage

Garrity-

My 86 951 has oil in the intake tract and the intercooler - like all of them. My turbine is fine - no play and smooth spinning.

I figure that over the years, oil has accumulated in the intercooler and thus reduced the efficiency of the intercooler. I have always wondered how to clean out an intercooler. Since you mentioned gasoline or solvent, do you have any tricks up your sleeve for a good way to do this?

BTW, are you going to be at the Carrera Classic this weekend at Gateway? I would love to meet another local Porschephile/Pelicanhead! I was just making a list of things to take before I make run to Wal-Mart.

-g