pointFive

My car has had an engine hesitation/sputter for quite some time now (please refer to Thread: 1985.5 Porsche 944 Engine Hesitation) and finding myself at a stalemate in regards to possible causes of the hesitation.

In summary, the engine hesitates at idle only. The RPM's will fluctuate between 800-1000. By setting the idle speed above US specifications (1100 RPM vs. 900 ± 50 RPM), it seems that the engine is less susceptible to the hesitation; however, it still exists. There is also a heavy smell of gas whenever I have the sunroof and windows open (I don't recall experiencing such a strong odor when I first bought the car). Lastly, on some cold starts, the car will "putt' its way through first gear...

I noticed the last time I changed the oil; there was a good amount of oil residue on the engine. Are there idling components of an engine that perform, negatively, by an oil leak? I don't plan to replace the rear main seal until I replace the clutch (hopefully by the end of summer), but I thought I would replace the cam tower gasket and various other parts/gaskets while the engine will be partially disassembled. In the 1985.5 Porsche 944 Engine Hesitation thread, it was suggested that I replace the vacuum lines/hoses. I also plan to replace the intake & exhaust manifold gaskets.

Are there any tips, tricks, or suggestions for this procedure?

harveyf

I didn't read the other thread but whomever mentioned vacuum lines and hoses was spot on. Any air leak downstream of the air flow flappy meter will lean out the mixture, most noticeably at idle. There are a lot of hoses. Not just little 3/8" diameter vacuum hoses but the bigger ones that mostly reside under the intake manifold. By the time you get to the cam tower, you will have exposed all of them. If you have the funds, just replace everything will new OEM hoses. It will be hundreds of dollars but I can guarantee that your will find either rock hard 30 year old hoses or a rats nest of half *** repairs using non OEM parts. Replace everything, including the big J boot. Also hoses leading to the brake booster and the fuel evaporative recovery tank system. You will be rewarded. Clarks-Garage.com has excellent tutorials on these types of repair jobs.

The gas smell is troubling. You have multiple 30 year old fuel lines. Supply from the tank/pump. Return back to the tank. And the gas vapor recovery system. Figure out a way to "sniff" the various components and hopefully isolate the problem. Download the PET (parts drawings) from Porsche website to help you get familiar with the various components.

pauldvazquez

Recently, I learned that the injectors themselves can become prone to leakage as well. After replacing the engine bay fuel lines, two injectors started leaking. I replaced all the injectors. Doing this had the pleasant side effect of improving the low speed drive ability immensely.

pointFive

@harveyf I was unaware of the PET (parts drawings) from Porsche website. Very helpful! Also, I do plan on replacing all the vacuum hoses; are there any other components that would be categorized as "must-replace" in the vicinity of the cam tower/intake manifold?

Speaking of components, where is the location of this part, 92810518400, and should be it replaced? Lastly, the car is a 1985.5 Porsche 944. Are there components specifically for a 1985.5 that should be highlighted to avoid ordering the wrong part number?

@pauldvazquez Good to know. I plan on inspecting the injectors and replacing their seals...

harveyf

Once you open the PET as a pdf, I have had pretty good luck doing Ctrl-F and searching on part numbers. I think it is best to leave out the dashes and spaces but always a good idea to search on a part number that you can see in the PET and see if your search technique finds it.

92810518400 is a camshaft housing seal. Go to my website www.newhillgarage.com and read the articles for the 944 engine rebuild. I think there is a picture of it in article 3?

I'm sure you know the biggest change for 85.5 is the dash. As you can probably see, there is a PET for 82-85 and another one for 85-88. I suspect the 85-88 would be the best starting point for you. In many cases, the part number may change based on engine number rather than the year of the car. The engine number is stamped into the side of the block. Drivers side, right next to the joint between the block and the clutch bell housing. It will clearly be easier to see after you get the manifold off. Snap a picture and email it to yourself for future reference.

I would replace the seals on the plastic black housing, with the orange cap, where you add oil. I would replace the Temp-II sender. Someone mentioned fuel injectors. I think sending the injectors to WitchHunter.com is good for peace of mind and money well spent. That will also get you new injector seals, on the chance that you have a leak where the injector stabs into the manifold. An air leak there will also affect idle and low speed. And will rule out injectors as source of your gas smell.

Label the plugs for the wires leading to the Speed and Reference sensors. You may find the plugs to be falling apart, which is common

You may just want to get a entire top end gasket kit (typically Victor-Reinz) from your favorite parts house.

If you haven't already started, I would clean the engine with Gunk or similar. Then run it some more before you take it apart. This may allow you to see the source of any fresh oil leaks.

Good luck!

pointFive

@harveyf I spent some time on your website; very enlightening! Will certainly refer to these articles...I was unable to find the camshaft housing seal picture, however. Nevertheless, where exactly is this part located and should it be replaced? An actual picture of the seal in it's true position would be very helpful!

I plan on submitting my order in today. When you mentioned the seals on the plastic black housing, are you referring to the AOS seals? Also, being that this is my daily driver, I'm unable to send the injectors out to WitchHunter.com. Hopefully they're in acceptable condition...

Regarding the timing belt, is there a method I should practice/follow when it's time to assemble? Needless to say, I don't have the factory timing belt tensioning tool...

harveyf

Yes, AOS seals.

I don't want to be a wet blanket but you really should not be doing the cam tower without the proper tools, which include a tensioning tool for the timing belt, torque wrench, long reach allen wrenches, triple square sockets, etc. Most are discussed in my engine rebuild articles. FYI the Arnnworx tool kit is a cost effective alternative to the factory tensioning tool.

If you are just trying to address a miss, I would not disturb the cam tower and/or the timing/balance belts at this time. Get all the various hoses associated with the intake manifold in tip top shape and then go from there. Unless there is some problem you are not describing, I don't see any way that the cam tower is causing your symptoms.

It might be worth checking with Witchhunter to see if they can work something out with some injectors they have on hand. You never know. Alternatively, there are ways to check the injector spray pattern "in-place". Check youtube. Just be damn careful.

pointFive

Well, I certainly have an oil leak; maybe in more than one place but I do know its leaking between the cam housing and cylinder head. I thought I'd address the leak, then replace anything related to idling issues within the vicinity of the cam housing...

I'm worried that the leak is decreasing the life of some components (starter, motor mounts, PS system) as there's a layer of oil residue on them...

I have all the proper tools besides the tensioning tool. I will look in the Arnnworx tool kit for sure.

Maybe I will just focus on whats causing the poor idle and acceleration now, then address the oil leak another time.

So would you suggest I replace all the hoses under the intake manifold, the AOS seals, intake manifold gaskets, J-boot, and idle control valve? Anything else worth replacing?

harveyf

First, the small o ring you asked about previously is behind the camshaft sprocket. You will not likely be breaking that connection apart.

Yes, that list of items is about it. Unfortunately, things can pop up while you're in there. No way around that.

I understand you want to tackle the oil leak. You will probably find more leaks as you get in there. The various seals for the balance shafts, etc. are always candidates for leaks. If you are trying to keep the car drivable, bite it off in small chunks. So yes, I would focus on the "top end refresh". If that goes well, then removing the cam tower would be the next step but it will go much faster if you've already tackled the inlet manifold.

harveyf

You might also consider doing a timing and balance belt replacement as a solo job. The Arnnworx tool works fine but there is a little bit of a learning curve before you get comfortable with using it.

In general, I find that most jobs on a "virgin" 944 engine that has not been dis-assembled in many years, if forever, results in some sort of aw****. Something breaks or snaps or was failed before you got in there. Best to take it in small chunks if its a daily driver.

wildcat077

The camshaft seals you need are in the PET on page 28
Parts 22 and 23 , although #22 oil seal has two dimensions , one is 30 x 47 and the other is 32 x 47, you have to verify what's installed on your engine , and part # 23 is a transparent paper thin gasket p/n 944 105 321 00

I've had many oil leaks with my previous race engine and #23 was the cause of one of them !