Dealing with an engine with oil blow-by - hoping for some thoughts and coaching on options Options

[Tdskip]

OK - so here is the scoop on the '74 AZ car that has me about to learn new things.

This is the car that has the 2.0l case with 1.8 heads. Runs strong, good pulling power, no bad noises, and has good oil pressure. Came to me with a recently put together engine with no guarantees but believed to be redone heads and fresh bottom end. Price was right on everything so I bought it, no regrets.

The issue I am seeing is that the engine has too much blow-by. After a short time (under 30 miles) it started smoking very noticeably from the breather and blew out the oil seal on the breather tower.

Since then I've changed the oil and done more heat cycling and it's smoking significantly less (barely noticable now) but I still have too much blow-by. I don't think I have much to loose by driving it some more and seeing if the rings seat better but I am working on the expectation that isn't going to work.

Assuming the most likely case, which is that the rings don't seat any better, I believe I would need to pull the heads and pistons off and start again. Yes/no?

Should I be thinking of just replacing the jugs and pistons with a new set from AA or do these clean up (in general). I believe replacement is the usual approach these days.

I think I would plan to send the heads out for servicing as a precaution so I know I have good ones with good oil control going back on.

Assembly from this point should be pretty straight forward I'd think?

Thanks, appreciate the continuing education here.

[rhodyguy]

Does the fill tower have a hose nipple on it? Where are the vapors being drawn off to?

[Tdskip]

Does the fill tower have a hose nipple on it? Where are the vapors being drawn off to?

@rhodyguy - hope you are well.

It does have a nipple on it and it vents to the carb (single Weber currently).

[tejon007]

OK - so here is the scoop on the '74 AZ car that has me about to learn new things.

This is the car that has the 2.0l case with 1.8 heads. Runs strong, good pulling power, no bad noises, and has good oil pressure. Came to me with a recently put together engine with no guarantees but believed to be redone heads and fresh bottom end. Price was right on everything so I bought it, no regrets.

The issue I am seeing is that the engine has too much blow-by. After a short time (under 30 miles) it started smoking very noticeably from the breather and blew out the oil seal on the breather tower.

Since then I've changed the oil and done more heat cycling and it's smoking significantly less (barely noticable now) but I still have too much blow-by. I don't think I have much to loose by driving it some more and seeing if the rings seat better but I am working on the expectation that isn't going to work.

Assuming the most likely case, which is that the rings don't seat any better, I believe I would need to pull the heads and pistons off and start again. Yes/no?

Should I be thinking of just replacing the jugs and pistons with a new set from AA or do these clean up (in general). I believe replacement is the usual approach these days.

I think I would plan to send the heads out for servicing as a precaution so I know I have good ones with good oil control going back on.

Assembly from this point should be pretty straight forward I'd think?

Thanks, appreciate the continuing education here.

Well, many possibilities for too much blowby. Could be past the rings - worn, improperly seated, "clocked" incorrectly (i.e. All ring gaps line up with each other), etc. Compression and leak down test results are what?

And, since you say you have 1.8 heads and other mix and match parts (2 liter case)...do the heads have the EGR holes? If so, where did you route them? (Could block them). If done wrong, this could make a tremendous blowby problem...

Best wishes with the fix!

[Tdskip]

@tejon007 - thank you for the response. I didn’t build this engine so I don’t know if any of the internal stuff was done improperly, but I will check to see what they did with the EGR openings. I haven’t done a week down or compression test yet because I was thinking, perhaps incorrectly, that if the blow by doesn’t go away I was going to have to open everything up anyway and at that point it doesn’t really matter. I would imagine that a leak down/compression test would tell me which hole had a problem but it’s gonna have to be opened up to fix it anyway-right?

[jcd914]

Couple thoughts:
Since you don't have history on the engine there are too many unknown variables but it might still be seating in the rings and improve with milage. It can easily take a couple thousand miles to fully break in an engine.

You say it has a single Weber carb and runs well, so the engine has much more potential since the single carb on a flat four works poorly in general, meaning with better induction it could run really well.
The long flat intake runners with the single carb promotes air fuel seperation between the carb and the heads and fuel falls out of suspension. Warm climate help keep fuel in suspension but is not enough. Commonly the single carb is set up overly rich so there is still enough fuel in suspension for the engine to run on.
One of the potential issues you maybe dealing with is too much raw fuel getting to the cylinders from an overly rich mixture to make the carb seem to work. The concern here is with the excess fuel washing oil off your cylinder walls leading to rapid piston, ring and cylinder wear.

Test, don't guess.
Do compression test AND leak down and see what is going on.
If you tear down latter you will still want to know what the compression and leak down were before you took it apart.
Nothing like guessing about issues before you reassemble.

Jim

Note: No 1.8l 914 engines have EGR ports in the heads. Late 2.0l heads have Air Injection ports but that is just the 75/76 2.0l engines.

[Larmo63]

The single Weber carb thing is never something you actually WANT on one of these cars.

Just sayin'

[914_teener]

The single Weber carb thing is never something you actually WANT on one of these cars.

Just sayin'

(IMG:style_emoticons/default/agree.gif)

[tejon007]

Couple thoughts:
Since you don't have history on the engine there are too many unknown variables but it might still be seating in the rings and improve with milage. It can easily take a couple thousand miles to fully break in an engine.

You say it has a single Weber carb and runs well, so the engine has much more potential since the single carb on a flat four works poorly in general, meaning with better induction it could run really well.
The long flat intake runners with the single carb promotes air fuel seperation between the carb and the heads and fuel falls out of suspension. Warm climate help keep fuel in suspension but is not enough. Commonly the single carb is set up overly rich so there is still enough fuel in suspension for the engine to run on.
One of the potential issues you maybe dealing with is too much raw fuel getting to the cylinders from an overly rich mixture to make the carb seem to work. The concern here is with the excess fuel washing oil off your cylinder walls leading to rapid piston, ring and cylinder wear.

Test, don't guess.
Do compression test AND leak down and see what is going on.
If you tear down latter you will still want to know what the compression and leak down were before you took it apart.
Nothing like guessing about issues before you reassemble.

Jim

Note: No 1.8l 914 engines have EGR ports in the heads. Late 2.0l heads have Air Injection ports but that is just the 75/76 2.0l engines.

Not true...I had a '72 with EGR heads (from a bus). Ok, so it's not normally an issue, but he said there was an unusually large amount of blowby. Shouldn't have even mentioned it...

Mixed and matched parts from unknown motors...could have heads with EGR ports as one possibility. If so, what was done? It's anyone's guess. Inspect and as we both said, perform compression and leak down testing...

So, whatever...less guessing and more testing.

My Best

[Tdskip]

The single Weber carb thing is never something you actually WANT on one of these cars.

Just sayin'

Good morning. It came like this and is not ideal but kind of a second-tier issue at this point. I have a spare set of Weber’s ear marked for when the time comes.

Thanks!

[Tdskip]

Breather set up - you can see where it blew out the cork seal. 2nd one it did that to.

[Tdskip]

[IronHillRestorations]

Sounds like the only "magic pill" is at minimum, a top end. Heads & rings, if you're lucky P & C kit more than likely, so add rod bearings and getting the rods rebushed.

[colingreene]

you need to do a leak down test or otherwise this is just pissing into the wind.

[jcd914]

you need to do a leak down test or otherwise this is just pissing into the wind.

(IMG:style_emoticons/default/agree.gif)

[tejon007]

Interested to find out the solution...so, please share the testing results when you have them.

It's weird that you blew out that gasket (twice) especially with the breather hose connected (and even if you're running with no vents in the heads or valve covers).

Is the breather housing restricted or plugged maybe??

[Tdskip]

Interested to find out the solution...so, please share the testing results when you have them.

It's weird that you blew out that gasket (twice) especially with the breather hose connected (and even if you're running with no vents in the heads or valve covers).

Is the breather housing restricted or plugged maybe??

Hi guys-should be able to get gauges on this car over the weekend.

@tejon007 - that is weird isn’t it, it was allowing airflow into the carb because you could see smoke coming out of the carb although that has significantly diminished the last couple times I ran it. There is still pretty good puffing coming from the oil filler cap when you remove it, it might be interesting to run it for a bit with the cap off ( with the car being stationary and making sure nothing gets into the engine via the cat being removed ) to see if that happens again.

[rhodyguy]

Oil smoke from the carpet? (IMG:style_emoticons/default/dry.gif) (IMG:style_emoticons/default/WTF.gif)

[Tdskip]

@rhodyguy - oops! That was supposed to say “carb”, Siri switched the word out and I didn’t catch it. Sorry!

Just had a quick chat with a well regarded engine builder, the shop who did my 2002 Tii engine, but also builds a lot of air cooled engines, and he said it almost certainly needs to come apart and it’s likely one or more broken rings. Until you open it up you never know but I’m inclined to agree with him.

[Tdskip]

@IronHillRestorations
@tejon007
@jcd914
@rhodyguy

First of all, good morning and happy Friday gentlemen.

I drove this car quite a bit yesterday and heat cycled the engine, did lots of rolling full throttle acceleration pulls and no change in the blow-by. I didn’t really expect it to suddenly improve but not much to lose by giving it another go.

Going to pull the plugs today and see if I can find out which cylinder is problematic, but the thing that has me scratching my head is that it actually runs well and has quite good power and doesn’t smoke out the tailpipe Even taking into account that this car is somewhat stripped , and is thus a bit lighter, the engine feels really healthy and strong even with the single Weber.

So with all that in mind here is the question that I was hoping to get some thoughts on-I think it’s one that’s relevant to the knowledge base here in general which is also why am asking - how can this thing be making good power if the problem is with the rings? I would have thought that if the rings are letting this much blow by happen that it would also be impacting compression to a point where the engine would be off song.

For education purposes other than rings, what internal to the engine would cause excessive crank case pressure?