[WA-Alfa]

Ever heard of leave well alone. Well I pulled my inlet manifold and sent it off to an engine reconditioner to clean with instructions to remove the coolant plug and the brake check value. Both are shown below.



You can see that for the coolant plug/tap/adaptor thingy the thread has fused with the inlet manifold and while most of the thread inside the manifold is ok the thread on the little plug/tap is not. Does anyone know where I might get a replacement for this.

I also wondered about the brake check valve shown above. My understanding is that this should suck vacume from the Number 4 cylinder and therefore air should only be able to travel one way through it. However I can suck air through it easily but I can also blow air through it too (although in a less restricted way). That is, I would be able to blow air through the check valve into number 4 cyclinder. Is this correct or is my check valve broken also.

 

[Gordon Raymond]

The check valve is history. It's a one way valve. Pretty easy to find on the used market.
Try Dean Russell @ Trail Auto, 313-561-3327. The heater nipple might be harder. Ask Dean. These are often corroded like yours. Correct fitment used a copper or aluminum washer underneath. Reinstallation only needs a little Permatex Ultra-Grey on the threads washer and back of the nipple to seal. These are often replaced with brass if you can find a matching thread. For my own use, I've turned a couple of these out of stainless steel and media blasted them to look like the original silver cadmium plating.
If you have a lathe, this isn't hard. If you have to pay someone to make one, it's way too expensive. Find a used one that's good, or a replacement brass nipple. Just my opinion from my experience.

 

[WA-Alfa]

Thanks Gordon.

I just went online and found a brand new brake check valve from Centreline. As for that nipple I recon with visit to a plumbing and hose supplier I should get something no trouble. Not stock but workable.

Thanks for your help BTW. I pulled the inlet manifold because I suspected that I had an air leak in the manifold so I am very eager to see what sort of difference changing the check value and fixing the leak will have for my compression - Number 4 cylinder has always gone though plugs way too quickly and its compression was always worse when compared to the other three.

I would imagine that you should get those Webers very soon too

 

[jonessjon]

Substitute the vacuum check valve with a brass nipple and get an inline one off a late model car from any wreckers

 

[alfazagato]

You could easily run a die ( or even a thread file) down the thread of the nipple and clear out the aluminium and similarly run a helicoil in the manifold to get back to a strong fitting. As Gordon says a stainless replacement is the way to go.

 

[Alfajay]

As for that nipple I recon with visit to a plumbing and hose supplier I should get something no trouble. Not stock but workable.

Uh, I hope it's that easy. If it is, please report back. My concern is that plumbing parts usually have tapered threads, while that heater outlet has a straight thread.

Number 4 cylinder has always gone though plugs way too quickly and its compression was always worse when compared to the other three.

Don't mean to sound negative here, but I'm not optimistic changing the valve will solve your plug and compression problems. It is possible that the leaking check valve has caused the mixture in #4 to be too lean, resulting in a burned valve and in turn, low compression. But, just replacing the bad check valve won't heal the burnt intake/exhaust valve.

By "gone though plugs way too quickly" do you mean they become oil-fouled, or that their electrodes get cooked?

 

[WA-Alfa]

Alfajay, I had the head replaced about 1,100km ago as it happens after my unfortunate accident caused by my own carelessness

http://www.alfabb.com/bb/forums/gt-...ts-way-into-combustion-camber.html#post976059

my plug on number 4 needed be be replaced 3 times within this 1,100km period after the head was reconditioned and replaced. I'm not sure if it was due to an over rich mixture or oil fouling but the black depositis seem more like carbon build up from an over rich mixture.

After the head was repalced there was however an intermitent spitting sound coming from the engine that at times I could feel through the accelerator pedal. I put it down to an inlet manifold leak. I guess I won't really know until I put it all back together. The engine would run on only three cylinders and I had to drive like this for some 10-20km before I could limp the car home to remove the offending plug shown below.



I did manage to pick the aluminium out of the thread and straingented it by using the check value thread as a comb. It might be ok but I'll try the plumbing store nonetheless for a nipple or two - I just love those 'naughty' trade words...

 

[Alfajay]

my plug on number 4 needed be be replaced 3 times within this 1,100km period after the head was reconditioned and replaced. I'm not sure if it was due to an over rich mixture or oil fouling but the black depositis seem more like carbon build up from an over rich mixture.

OK, thanks for clarifying that. I can picture the faulty brake vacuum check valve allowing air to bleed into #4 intake, causing an overly lean mixture. But I can't see how it would result in an over rich mixture. In other words, I'm skeptical that a vacuum leak is the cause for your sooty #4 plug. Might the rear carb be the issue? Or an oil leak (rings, valve seals) on #4?

Maybe you had both a lean mixture from the vacuum leak that caused the "spitting" and oil getting into #4 cylinder that fouled the plug. How is oil consumption? Any white smoke out the tailpipe on deceleration?

Let us know how the symptoms change once the vacuum leak is corrected.

 

[180OUT]

You could easily run a die ( or even a thread file) down the thread of the nipple and clear out the aluminium and similarly run a helicoil in the manifold to get back to a strong fitting. As Gordon says a stainless replacement is the way to go.

PermaTex makes a thread repair compound designed for these kinds of problems. It's easy to use.

 

[eedneco]

To offer a few ideas / approaches, FWIW:
- if you remove that #4 plug soon after shutting down the motor, is it wetter (and smellier) with gas than the others ? I have trouble telling from the picture if it's fuel or oil or a mixture of both.
- But, as you mentioned the compression was worse on #4, there is a good likelihood that it is at least partly oil contamination. When the head was off, was #4 piston crown more crudded up than the others ? Have you tried with oil addition to see if the low compression is from rings or valves ? I wouldn't be surprised if it was rings, and indeed I wouldn't be too surprised if you have a broken ring in #4. Even through the spark plug holes, you may be able to see if there is any significant difference in the deposits on the tops of #4 versus the others. I had a problem once where a shop bent one of my rods while doing rebushing work, and I didn't detect it while putting the motor together. That piston was ****ed in the bore as a result and the rings couldn't work right. It took me a long time to find the problem after disassembly, but on the contrary, it was obvious from very early on that I had a problem in that cylinder because of the difference in the deposits compared to the others - that piston was obviously oily whereas the others had dry carbon on them.
Oil leaks into a particular cylinder can also be from a valve seal being damaged on installation, but if you say you also have compression issues then I would think we're much more likely to have an oil sealing issue with the rings ?
Did you or didn't you have this same oiling issue on #4 before the change of head ?
If it's only developed since the change of head, then it may be a misassembly issue on a valve on #4, like a stem seal that didn't get installed right, is interfering somewhat with the valve travel, and is also leaking. Do you have high lift cams ? This can make things trickier in terms of ensuring enough space between the stem seals and the spring retainers.

/Neil

 

[WA-Alfa]

Not sure. If it is was way too lean due to an air leak then the plug will foul due to failure to combust the fuel and then the plug develops carbon deposists?? An over rich mixture would also produce the same outcome eventually no?

I think i probably have three problems, an air leak in the manifold, leak due to the brake check value and probably a very old carby in need of a good overhaul.

 

[WA-Alfa]

and yes as Neil says probably a not too good set of rings on cylinder 4 as well. In about 20,000km I changed the plug 3 times on cylinder 4 and this was before the head was replaced/rebuilt. So I've clearly got a range of problems and a lower engine rebuilt is really the only thing I think that will fix it.