worf928

I can't keep up Tired. Terse response:

Order parts from 928sRUs, 928 International, 928 Specialists, Sunset Porsche, etc. No-name parts from random places are - at best - a total crap shoot and usually end up costing you enough time that any extra money for 'real' parts is a wash.

Earlier post about engine getting hot is worrisome. Procedure is: fill engine with coolant from upper radiator hose. Fill radiator from lower hose. Fill reservoir to seam. Turn heat on full hot to ensure coolant will circulate through heater core. If you are not certain that the fans work, bench test them with a power supply before you install the fan shroud. Start car, check oil pressure, coolant level warning light. Allow to idle checking temperature of upper and lower hose. Upper hose will get warm. Lower hose will stay cool until thermostat opens. On '89+ you can watch temp gauge if you know it works. Otherwise use external temperature measurement device of some sort pointed at the water bridge above the thermostat. Thermostat begins opening at ~175 and fully open by ~185 IIRC. At that point lower hose should be hot. Coolant level in reservoir should drop. If reservoir empties, shut off car. Allow to cool. Refill. Lather, rinse repeat. If reservoir doesn't drop too far, idle until fans on at ~205 IIRC. Then shut down. Cool. Lather, rinse repeat.

Deviation from that - hose temps, no reservoir drop first time, no fans, etc. - means off-nominal condition that requires investigation. You don't want air pockets in the motor for any length of time.

Crap cap explains smoke. Unexplained is wear pattern on timing belt IF the wear pattern is new. Is it possible that the wear was there before you started?

Belt noise could be air pump or a/c compressor pulley. Former like to make noise if they have not rotated in a long time. Compressor clutch bearings can fail. Remove belts (or cut off if they are to be replaced anyway) sequentially until noise goes away. (Or use stethoscope to isolate.)

worf928

Cam covers and intake and related are looking good. Nice job.

There's a lot of noise on that. Noise could be from the air pump, compressor or water pump.

Is there any refrigerant in the A/C system? If so, cycling the compressor on-and-off should change the noise characteristics if it's from the clutch. (If no gas in the A/C, compressor clutch will not engage.)

Alternatively, loosening slightly, each belt sequentially, might result in a tone change.

Chalkboss

Great advice as always from Worf. I notice in the video you have no jump post cover. You should get one to protect the connector. Looking good, you're almost there!

msteiner805

Thanks Dave,

98% of the parts I've ordered have been from the above mentioned suppliers (mostly from Roger). Sometimes I see a deal that's too good to be true, like the cheap caps, and I'll bite. Sometimes I get lucky and everything works well and sometimes its a waste of time. You're right its a crap shoot.

Per the over-heating, I did not follow the initial process you mentioned above regarding filling the coolant (out of ignorance) - I only filled the reservoir - on initial start-up the engine did not have much coolant. The reservoir emptied again yesterday and the engine temp remained stable right in the middle of the gauge. The lower hose got hot as well and then the fans turned on. I'm attributing the initial over-heating to improper coolant fill procedure. All seems good now

I checked photos of the timing belt prior to new cap - and - the wear pattern was always there. Red herring.

Per the bearing noise : I charged the A/C a couple months ago and I do get cold air out of the vents. The note of the engine does not change much when I turn on/off the A/C - the bearing noise is still there whether a/c is engaged or not.

I'm getting a stethoscope today and will attempt to isolate the noise further. Will report back soon.

Mike

FredR

Mike,

Kind of amusing to see you have got your first "brain fart" out of the way with little consequence other than a few bucks down the can - the dist cap is a classic- return them and demand your money back!

You could try pulling the belts off one at a time to test for noise modulation. You can also isolate the fans from their power supply- the fan motors make quite a noise when they go and of course their noise is not linked to engine rpms- something to consider.

Given all you have done to date, as per earlier advice I would seriously consider pulling the timing belt if you do not know the history of this item and simply get it out of the way for another 5 years at least. Same for the water pump and idler pinions [the latter if needed]. If the water pump is relatively new you could consider reusing it albeit this is debatable.

Regards

Fred

msteiner805

Hi Fred,

Yeah, the dist cap was a good one . I've had a lot of brain farts in this process and I'm sure more will come. I'll document the more interesting ones here as they happen.

Per the potential bearing noise, I was able to get a hold of an automotive stethoscope so I checked the alternator, water pump and A/C compressor. All sound nice - the alternator has a slight bearing noise, but not too bad yet.

I wasn't able to get a clear stethoscope path to the air pump... will give it another shot tonight or maybe tomorrow.

Per the timing belt - I'll be doing the job this month. Still debating parts selection.

- Do I rebuild the original tensioner? Or go with the PKtensioner?

- Do I go with a Laso pump or the Gaurdian?

I haven't made up my mind yet about those two items... Also, does anyone know of who can re-coat cam gears locally in Central/Southern California?

Mike

worf928

Ok. That was not a good thing to do. Hopefully it only ran for a short while and - so far, so good - no damage has occurred. Time will tell.

Ok. So, if the bearing noise didn't change then it's not the compressor pulley. I assume you noticed whether or not the clutch engaged when the A/C was activated.

Other than the two below there's no selection process.
Idle Roller
Main tention roller.
Tensioner piston o-ring
Tensioner boot and clamp.
Tensioner gasket.
Roller carrier bushings. (They are stupid expensive, but they must be replaced.)
That's a religous war. Pick your deity.

I don't believe the Laso is an option unless Roger has a few stashed away or you want to modify a pump from an early car. There was a recent thread on this.

If you are thinking about leaving the existing pump, then you must at least pull it and determine if
a) the impeller has migrated
b) the impeller is metal and the pump isn't 1) known to be a 'good' Laso or 2) known to have been a new-at-the-time pump.

It's highly likely that the pump in the car is a rebuilt. If it has a metal impeller it has to go.

As for gears, if your cam sprockets are worn to the point of needing re-coating then your oil pump gear will be in the same condition. You will also need to closely examine the crank gear to see if it exhibits a wear pattern. If it does it will need to go too.

msteiner805

Thanks Dave,

Yeah, initially I ran the car for a very short time maybe 10mins total over multiple starts. I noticed the temperature rising too quickly and stopped right away. The needle never went into the red zone, maybe 200 max.

Thanks for the advice per the tb change. Still debating which parts to go with. Roger is going to price out my options and that will help me decide as well.

Mike

msteiner805

Managed to get the stethoscope on the air pump and it sounds terrible! Lots of grinding shuddering noises. Going to do some research on rebuilding / replacing.


Mike

Bertrand Daoust

http://members.rennlist.com/mgrasser/airpumprebuild.htm

I hope this will help.

msteiner805

Thank You - that is a good link, very useful and helpful.

Looks like there are quite few bearings in there that will likely need to be replaced. Do you know if the author is still active? I sent an email to him with questions about part numbers but got rejected email server messages.

I did find a source here: https://rennlist.com/forums/928-foru...p-rebuild.html

Wholesale Bearing and Drive Supply Telephone: 305-573-7678 E-Mail: sales@wbds.com

Front bearing - 6203 RS - $2
Large rear roller bearing B188 $5
Small vane bearing (4) B65 $4 each


Mike

FredR

Mike,

Would your 928 pass California smog tests if the air pump was permanently disconnected? As I understand the thing was a factory frig to help the motor pass the strict California emission regs when they were introduced and make no real world difference to the state of the planet whatsoever.

I seem to remember someone saying they could pass the smog regs without the air pump but whether it was in California no idea.

Rgds

Fred

msteiner805

Hi Fred,

This smog pump issue is something I've been giving some thought to. I think you're right that the car would probably pass without the smog pump, but, there seems to be some concern about reduced cat life when the pump is removed:

https://rennlist.com/forums/928-foru...smog-pump.html

In any case, Porsche put the pump in there and I want an all-original car so the air pump is staying

That said, I'm seriously considering the PK-tensioner. I know I just said I want an original car so call me hypocrite LOL, but, the PK-tensioner is a better engineered solution that is in-line with the original system intent and design. Roger said it best when he speculated that Porsche was likely going to use the Audi tensioner going forward had Porsche continued production the 928.

So that's where my belief system sits on the all original car topic. If Porsche put the system in place, then that system is staying as is. Unless that system has obvious flaws, or, has a safety issues. For example, lifetime fuel lines and a better belt tensioner system fall into the safety/flaw case, respectively.

Mike

msteiner805

Hi All,

Going to have to wait a little while before I tackle the timing belt. My time has been limited lately. Have the bearings for the smog pump on order.

While waiting, there is other behavior I'd like to get some advice on : my A/C stopped blowing cold (it still blows cool) shortly after I recharged the system and here is some data:

- There is a decent amount of refrigerant in the system and no leaks. I can check for leaks again as this was several months ago when I checked last.
- The compressor clutch engages and I see quite a bit of frost on the cold lines near the compressor.
- I've replaced the heater control valve with a new unit when I did the intake refresh. It holds vacuum.
- When on, the rear A/C unit blows much colder than the dash A/C.
- Orange line from the center console HVAC manifold won't hold any vacuum. All other lines at the manifold hold vacuum.

The orange line controls the comb flap actuator, correct? Would a lack of vacuum here cause a mix of hot air? Is this only issue I should address before reassembly?

Mike

teeth

Hello from your car's twin brother in San Diego!