WTF bearing fretting

[Einspritz]

Not just compression, leakdown too. When you pump air into the cylinder(s), listen at the Throttle Body (intake valve leak), the Exhaust pipe (exhaust valve leak) , and if you can at the dipstick (compression ring leak).

 

I don't know about Comp Turbo's qualifications.

 

I used Diamond Diesel in Oakland, CA for two rebuilds without issue. Well, except on the most recent rebuild they painted the exhaust housing and removed the OE intake plate to affix their own. Then again, I didn't specify "what not to touch".

 

Call Dave at Precision about your pump.

[m6smitten]

Thanks for your valuable input. What’s the full name for Precision? Location?

 

[Einspritz]

Precision Automotive Research

 

http://www.precisionautoresearch.com/

 

Dave Redszus Sr.

 

or David Redszus, PHd.

 

630-766-4402

[allbim]

Is the surface that the OD of the bushings rub against, smooth?

[Einspritz]

huh?

[m6smitten]

I am interested to hear more. Kent Goldy ( of Cosworth), the guy who remans turbos for Carl Nelson mentioned he bores them out and installs a larger bearing.

[Einspritz]

I don't' understand why this is an issue.

 

My rebuilder said it was no problem to get bearings and seals from "stock" without any modifications. I just never pressed him to put together kits, because, well "I got mine".

 

IIRC two years ago they were the same as  from a K27.

 

Have your guy check to see if it is true, if not get back to me and I will go down to my rebuilder.

[m6smitten]

I was curious to hear what Allbim had to say. 

 

Since my rebuild, I have had oil getting past the turbo seals and leaking into the compressor housing. and into the inlet tube. Thought it may be bearing related but local turbo (Diesel)guy took it apart and said bearing was OK - he said it may be bad oil drain.

I have replaced the stock oil return  three times with a larger diameter hose each time. I am up to a 16 AN now and will update after install. 

 

[jimk]

Is the drain routing such that there is a constant slope to the pan drain point with no low point traps?  Absolutely clear drainage is a must or oil back up will happen.  Oil comes out of the bearing housing looking like whipped cream and a good drain path.

Edited September 24, 2019 by jimk

[Einspritz]

On 9/11/2019 at 7:49 PM, allbim said:

s the surface that the OD of the bushings rub against, smooth?

 I  looked at this over the weekend and saw that the bushings / bearings do not touch the OD wall, they are free floating.

 

55 minutes ago, jimk said:

Is the drain routing such that there is a constant slope to the pan drain point with no low point traps?

 

Yes. otherwise your hose is too long.

 

55 minutes ago, jimk said:

Absolutely clear drainage is a must or oil back up will happen.  Oil comes out of the bearing housing looking like whipped cream and a good drain path.

 

is that a question or a statement? :) Either way the answer is yes.

 

[m6smitten]

Good points you two. I will post a pic of my install. 

 

Oil pressure is within spec too. 

[Einspritz]

On 9/23/2019 at 1:31 PM, m6smitten said:

I have had oil getting past the turbo seals and leaking into the compressor housing. and into the inlet tube.

 

Forgot to answer this.

 

Mine does this, but I don't worry about it much. I would say it is caused when there is a vacuum in the tubes sucking out the oil, e.g. long runs at less than "in the green zone" of boost, like highway cruising......remember that there is some obstruction with the air filter causing a vacuum.....which your gauge displays.

 

If only the plenum is oiled, then check the plug on the back of the pump for oil accumulation, there should be none, indicative of a seal failure. In a worst case scenario, that chamber fills up hydro locking the piston inside the housing making it impossible to get fuel enrichment under boost and to tune. The pathway is through the brake booster circuit hoses into the plenum only......

 

Now, if it is constantly fouling your plugs, then you need to stop idling so much,  or just driving around town; get out and exercise the car.

 

Spare set of plugs in the trunk or 40 Kv coil not included not included.......

[m6smitten]

Did not think about vacuum in the inlet sucking oil through seals. Makes sense.

This plug? 

Edited September 25, 2019 by m6smitten

[Einspritz]

no. that is the fuel return for a standard Tii pump.

 

On the Turbo pump, follow the two hoses, which are brake booster hose type, one from the altitude compensator and another from the "three way" fitment with a vacuum port for the distributor to the bottom attachment to the aneroid casting (the big cylindrical casting on the back) . There you will find IIRC a 22mm or 24 mm hex plug, which in effect accesses the mechanism for enrichment. It is kinda like the crankcase of an engine in that there is a "crank" that goes into the back of the pump proper with a rod and piston(there is a small hole in the piston which allows air to pass) that moves up and down with corresponding vacuum or boost. Full vacuum moves the piston one way and boost moves it the other way moving the internal cam to provide enrichment.

 

But I digress.

 

Remove that plug, if oil comes out then you have a seal problem as oil from the pump internals is allowed to leak. As I said, if too much oil leaks into that chamber it can hydro-lock the movement of the piston, necessitating a servicing of the pump. I figure it is time related, and I don't think particularly mileage related, as the seal ages it loses its ability to seal, particularly when exposed to high vacuum and boost. When replaced, a "cheepie" seal is not particularly cost effective nor prudent.

 

It is very important to note that the Turbo pump, unlike the tii pump which delivers fuel as a function of engine speed directly, meters fuel as a function of engine speed AND vacuum or boost. Any proper refurbishment of the Turbo pump MUST include the altitude compensator (the disk shaped part with a filter bolted to the fender) and calibrated under different levels of vacuum and boost. Under vacuum air is drawn into the system via the "V Groove" covered partially by the white plastic block and actuated by the sealed brass accordian. Under boost, excess air is blown out through the same path. As you go up in altitude, the accordian expands changing the amount of air allowed in the system under vacuum. Nifty.

[jimk]

On 9/24/2019 at 3:25 PM, Einspritz said:

I would say it is caused when there is a vacuum in the tubes sucking out the oil, e.g. long runs at less than "in the green zone" of boost, like highway cruising.

I thought the throttle was downstream of the compressor.  If so how does the compressor side develop vacuum unless there is a severe restriction in the air filtration system?

 

On 9/23/2019 at 8:07 PM, Einspritz said:

bearings do not touch the OD wall, they are free floating.

Yes because the turbo rotor/shaft spins above critical rotor speed.  It passes thru critical speed each time it spools up.  If they were not free floating the bearings would be eaten up almost immediately because at speeds above critical the shaft rotates around the center of mass, not the geometric center.