Engine trouble

[greencom]

Hi Guys,
I'm hoping someone out there can give me some insight into a really vexing problem that came up. The engine in my '52 M37 will not idle unless I apply almost full choke, it will die if I start to open the choke. It will run at high rpm with the choke open but nothing below about 1000 rpm. I took the carb off my good running truck and used it and had the same problem. I'm thinking maybe bad intake manifold gasket or cracked intake manifold. I would really appreciate some help, you guys are a real resource.
Greencom

[Lifer]

Changing to a known good carb didn't help, huh? Two options come to mind: not enough fuel or too much air.

Check for adequate fuel pressure at the output side of the pump first.

If you have plenty of fuel, check for an air leak. Could be a bad carb gasket, a bad intake manifold gasket, a cracked (or broken) intake manifold, or even a simple vacuum leak.

[greencom]

Hey Lifer, thanks for the reply. Actually I've been using a gravity feed for about a year now, I know that's not much pressure but it has been working great for me up till now. I'm suspecting a manifold gasket too. I'm now wondering if I have a possible distributor problem that has caused the spark to retard to the point that a lot of vacuum is lost and not enough is there to pull the fuel from the carb's idle circuit. Just a thought, whaddya think?
Greencom

[Lifer]

Gravity feed should work just fine, as long as you don't try to climb any steep hills. Feeding it into a working fuel pump would ensure consistent fuel pressure, though.

Sounds like you need to check the gasket(s).

[MSeriesRebuild]

Hi Guys,
I'm hoping someone out there can give me some insight into a really vexing problem that came up. The engine in my '52 M37 will not idle unless I apply almost full choke, it will die if I start to open the choke. It will run at high rpm with the choke open but nothing below about 1000 rpm. I took the carb off my good running truck and used it and had the same problem. I'm thinking maybe bad intake manifold gasket or cracked intake manifold. I would really appreciate some help, you guys are a real resource.
Greencom

What's the REAL condition of your engine? Don't get me wrong, I'd check other areas in a trouble shoot first, but if nothing turns up as the problem along the way, then you'll need to look at a compression check down the road. Assuming that you already know the fuel supply is plentiful without a doubt & that you are certain the 2nd carb you tried is in good shape, I would concentrate next on the area around the carb base & the intake manifold. Much of a leak will be obvious, however very small ones can be hard to pinpoint. Before I mention our method, let me say this, IF YOU DON"T FEEL SAFE DOING IT, BY ALL MEANS DON'T TRY IT. I'm not telling you to use my method, just sharing what has worked many times for us. Here's what I do to locate hard to find vacuum leaks. With the engine idling I use my acetylene torch with a small welding tip installed, turn on the gas (at a very low delivery setting) while moving the torch in & around the whole intake area. If fresh air is being pulled into the system as a result of a leak, as soon as the acetylene is pulled in, it will smooth out & run like a dream. Now that the leak source is found, you can go ahead & make a proper repair. NOW, before someone goes off on a tangent about the dangers of doing this let me add, I never do it on a hot engine & as always you must apply healthy portions of common sense. If I'm resorting to this method (it is a last resort for us), I use it on a cold engine, I mean cranking it the first time after it's set overnight, then troubleshoot with the torch immediately before it has a chance to warm up. If there is a leak, it will show up almost immediately before heat is an issue. Be absolutely SURE you keep the torch from contacting anything electrical or anything else that could be a source of ignition. Don't forget I said use liberal portions of common sense when doing this & be ready on the trigger to withdraw the torch from the area & cut gas off if you need too. It's also a good idea to have a cut-off man ready at the tank valve in the event you need him. A capable trained third man with known good fire extingusher in hand is standing by & ready at a moments call. We've used it many times, it's a virtually fool-proof test. It will show a leak very quickly if there is one in the neighborhood. Also be sure your acetylene hose is protected from being cut & not allowed to touch the exhaust manifold etc. Before testing for leaks, I would be sure that timing issues are solved in advance. No need to be doing further testing until you know that timing issues don't exist. Go through the proper procedure & set everything at a good default setting before cranking the engine. Also check the condition of your distributor, plugs, wires, etc., being sure you have a good hot spark. If these test net nothing, then you need to perform that compression test as it is becoming more evident that a deeper problem is hiding somewhere. I would assume since you are using an auxiliary fuel tank that your gas is FRESH. At any rate, USE FRESH FUEL, all sorts of problems can come from using gas that has been stored for a while.

[greencom]

Charles, thanks for the reply. I'm going to borrow my neighbor's torch outfit tomorrow and try to find the leak if there is one. I appreciate all the advice and your time.
Greencom

[greencom]

Charles,
I tried the acetylene test for vacuum leak, and heard no change in engine rpm or sound. That's because my compression is shot. I'm getting 60 psi in all cylinders. I squirted oil into one of the cylinders and it went up 30 psi so I have a ring/cylinder issue. I'm a bit stumped as to why the engine was running so well earlier with no blowby or idle problem. I was hoping it was a valve issue. Oh well, Off goes the head now , I want to check the look of the cylinders and take out a piston to check for stuck rings. This baby did sit for a very long time.
Greencom

[MSeriesRebuild]

Charles,
I tried the acetylene test for vacuum leak, and heard no change in engine rpm or sound. That's because my compression is shot. I'm getting 60 psi in all cylinders. I squirted oil into one of the cylinders and it went up 30 psi so I have a ring/cylinder issue. I'm a bit stumped as to why the engine was running so well earlier with no blowby or idle problem. I was hoping it was a valve issue. Oh well, Off goes the head now , I want to check the look of the cylinders and take out a piston to check for stuck rings. This baby did sit for a very long time.
Greencom

I was a little suspicious it might be a compression issue. It could be sticking rings has caused accelerated cylinder wall wear, they must float freely in their grooves to do their job correctly. I'm surprised it will run at all with only 60PSI. A full rebuild is the only alternative now.

[Dicktater]

[quote="greencom"]. I'm a bit stumped as to why the engine was running so well earlier with no blowby or idle problem.


COULD BE A CHANGE IN THE WEATHER,HAS THE TEMP. DROPED IN YOUR AREA RECENTLY??

[MSeriesRebuild]

If I understood correctly, you said you did the follow up test after adding oil to one cylinder. I would add oil & do a follow up test on each cylinder, if the pressure comes up significantly like the one did that you mentioned, then it's a done deal. You mentioned a concern as to why this seemed to show up all of a sudden, well the truth is cylinder wear doesn't happen all of a sudden. When we have engines come to us with similar problems, most of the time the report we get is similar & many times exactly like what you've said. When we take them down, seldom do we find anything that would indicate an all of a sudden break down. It's simply this, a buyer gets a truck, more than likely knows nothing of the real engine condition. It runs so no compression test is done to reveal the "real condition". Most new owners don't realize how the engine should & would perform if it were in top condition. They just drive, when it seems like major engine problems occur out of nowhere, it's hard for them to understand. In the vast majority of these situations, engine compression was in the lower end of the spectrum (many times borderline) from the time they got the truck. Especially when an engine has stood for years in storage or in many cases just sitting out somewhere, these circumstances take their toll. When the engine is put back into service, more often than not accelerated wear takes place because of various issues. One biggy in this area is that an engine that has sit idle for years will have surface rust formed on the cylinder walls & of course that will invade the cylinder wall surface causing minor pitting, etc. When the engine cranks up, this surface rust is scrapped off the walls by the rings in the first few hours it runs. Whatever pitting the rust caused is then exposed, the rings don't seal well against the walls because they are no longer smooth, just this can & will drop compression readings significantly. As the engine runs more, the compression you do have drops quickly into the unacceptable range. All of a sudden you start to see symptoms exactly like yours. Another killer is the fact that the rust that was scrapped off the walls is now in suspension with the engine oil. The abrasive rust traveling throughout the engines oil passages is now grinding away at other engine vitals. This information is of course now too little too late in your case, but if an engine has sit for a long time, the best thing to do is pull it down for at least a thorough clean out before it's cranked up. While you are spending money on the get go, you can save much over what may now be necessary to put the engine back into top condition. I've seen some really major damage done to bearing surfaces of the crank, cam, etc. when oil tainted with fine rust particles is run. It is a serious deal with a 230 engine as it has only by-pass type oil filtration with no full flow filter. The fine particles also have a tendancy to plug small oil passages, even heavier damage occurs when oil flow is restricted. My recommendation now would be to pull it down completely, clean & mic everything to see what wear has actually occured. I would be willing to bet you'll find other issues as well as excessive ring/cylinder wall wear.

[greencom]

I wish it was a weather issue Dictater, oh well. Charles, I'm sure you are spot on about my engine. At least it's in my beater truck that I originally bought for it's winch and parts. The guy I bought it from drove it onto a trailer so I was surprised it ran, that was a bonus. Later I decided to fix it up a little and use it around the farm. I am looking at this as an opportunity to bone up on engine rebuilding and am looking forward to it. The odd thing about engines is that my 1930 Ford has a normal spec compression pressure of around 62psi and runs like a clock (4.5 : 1 ratio). Thank you for all of your advice and if it's ok bother you now and again down the road.
Greencom

[MSeriesRebuild]

Call anytime, that's why we're here.