General motor question
General motor question
My son's ranger is slowly over heating. He took it somewhere and they told him they thought it had a blown head gasket. I just took a look at it last night and ran a compression check and I'm getting 120 to 130 on all 4 cylinders. There is no white foam/froth on the dipstick or the underside of the filler cap. I just don't see how this can be a blown head gasket.
My question to you is , is it possible to have a blown head gasket and good compression, I just do not think it is.
My question to you is , is it possible to have a blown head gasket and good compression, I just do not think it is.
JD- 450C track loader
Serial #208336T
Serial #208336T
Any bubbles in the radiator when it is running?
Lavoy
Lavoy
Parts and restoration for antique and late model John Deere crawlers.
Owner and moderator www.jdcrawlers.com
Owner and moderator www.jdcrawlers.com
- Stan Disbrow
- 350 crawler
- Posts: 2898
- Joined: Fri Jul 15, 2005 3:13 pm
- Location: Raleigh, NC
Hi,
Yes, one can have a tiny leak from the head gasket that puts only a little combustion gas in to the water jacket. Remember, the pressure in the cylinders is many times higher than what you see on a compression gauge due to the small bomb set off when it fires.
The tell-tale is gas bubbles in the top of the radiator when running. You will only see water vapor in the hot exhaust with a gross leak from the water jacket into the cylinder. But, the leak will start off minor most of the time.
Another thing to look at is the temperature of the water at the top of the radiator vs. the temperature of the water in the engine jacket. It is also possible that the thermostat is not opening, or opening enough. This will show as high temp in the engine jacket and low temp at the top of the radiator.
I have an F150 farm truck with a 302 which shows too hot early on, then drops off rapidly once the thermostat finally opens. I am too lazy to pull the intake manifold off and change the fool thing. So, I just put the heater in high for the few minutes where the temp is too high until the thermostat finally opens. That works out to be just enough cooling to avoid a real problem. One day, the thermostat will stay stuck closed, and I will finally have to do something about it....
Stan
Yes, one can have a tiny leak from the head gasket that puts only a little combustion gas in to the water jacket. Remember, the pressure in the cylinders is many times higher than what you see on a compression gauge due to the small bomb set off when it fires.
The tell-tale is gas bubbles in the top of the radiator when running. You will only see water vapor in the hot exhaust with a gross leak from the water jacket into the cylinder. But, the leak will start off minor most of the time.
Another thing to look at is the temperature of the water at the top of the radiator vs. the temperature of the water in the engine jacket. It is also possible that the thermostat is not opening, or opening enough. This will show as high temp in the engine jacket and low temp at the top of the radiator.
I have an F150 farm truck with a 302 which shows too hot early on, then drops off rapidly once the thermostat finally opens. I am too lazy to pull the intake manifold off and change the fool thing. So, I just put the heater in high for the few minutes where the temp is too high until the thermostat finally opens. That works out to be just enough cooling to avoid a real problem. One day, the thermostat will stay stuck closed, and I will finally have to do something about it....
Stan
There's No Such Thing As A Cheap Crawler!
Useta Have: '58 JD 420c 5-roller w/62 inside blade
Useta Have: '78 JD350C w/6310 outside blade
Useta Have: '68 JD350, '51 Terratrac GT-25
Have: 1950 M, 2005 x495, 2008 5103 (now known as 5045D)
Useta Have: '58 JD 420c 5-roller w/62 inside blade
Useta Have: '78 JD350C w/6310 outside blade
Useta Have: '68 JD350, '51 Terratrac GT-25
Have: 1950 M, 2005 x495, 2008 5103 (now known as 5045D)
Re: General motor question
A blown head gasket will show on compression if the break is between the combustion cylinder and the water passage- however it may not show a compression loss if the break is between a water and oil passage.77 Ford wrote:My son's ranger is slowly over heating. He took it somewhere and they told him they thought it had a blown head gasket. I just took a look at it last night and ran a compression check and I'm getting 120 to 130 on all 4 cylinders. There is no white foam/froth on the dipstick or the underside of the filler cap. I just don't see how this can be a blown head gasket.
My question to you is , is it possible to have a blown head gasket and good compression, I just do not think it is.
There is also such a thing as a "seeping" head gasket- this is common to Hondas and Acuras. The head gasket in that case is "blown" slightly between the combustion chamber and water passage- usually the rear cylinder which causes overheating. Due to the design the water doesn't enter the combustion chamber and the car will still run great (just overheat) but a compression test would detect leak down.
BTW, is your son's Ranger a late 80s/early 90s with the 2.9L 6-cylinder engine? If so there is a design flaw that can cause overheating. I can send you a web link to a good webpage that describes the issue- it has to do with the design of the cylinder heads. I only know about this because I thought about buying one recently and decided to pass after reading about the design flaw- the truck I was looking at had the tell-tale symptoms (overheating/white vapor from tailpipe but good compression).
(1) JD Straight 450 crawler dozer with manual outside blade; (2) JD 2010 diesel crawler loaders; (1) JD 2010 diesel dozer with hydraulic 6-way blade; (2) Model 50 backhoe attachments, misc. other construction equipment
Thanks everyone for the information, to answer a few questions. It's a 4 cyl ranger, I think it's an 89. It has the little engine with 2 plugs per cylinder.
I will check it for bubble when running next time I look at it. I'm really leaning towards a stuck open thermostat. The upper house warms up so I don't think it's stuck closed although i suppose it could be partial like someone else suggested.
It looks pretty easy to change the thermostat and it's not really out of the way towards doing a head job anyways.
Thanks!
Phillip
I will check it for bubble when running next time I look at it. I'm really leaning towards a stuck open thermostat. The upper house warms up so I don't think it's stuck closed although i suppose it could be partial like someone else suggested.
It looks pretty easy to change the thermostat and it's not really out of the way towards doing a head job anyways.
Thanks!
Phillip
JD- 450C track loader
Serial #208336T
Serial #208336T
Follow up:
It was a stuck closed thermostat. I pulled the thermostat and it would not open in pot at full boil. I asked my son how he did the upper hose was hot test (which normally checks for a closed thermostat) and he replied he check it after he had drove it for 45 minutes. I explained that test is really something you should do in just a few minutes of running that at 45 minutes it could of heated up thru under hood temperatures.
There was some oil in the water so it's possible there is still a head gasket issue but it's running good and we're only 15 bucks deep at this point so we're going to keep an eye on it for now.
It was a stuck closed thermostat. I pulled the thermostat and it would not open in pot at full boil. I asked my son how he did the upper hose was hot test (which normally checks for a closed thermostat) and he replied he check it after he had drove it for 45 minutes. I explained that test is really something you should do in just a few minutes of running that at 45 minutes it could of heated up thru under hood temperatures.
There was some oil in the water so it's possible there is still a head gasket issue but it's running good and we're only 15 bucks deep at this point so we're going to keep an eye on it for now.
JD- 450C track loader
Serial #208336T
Serial #208336T
Glad you did not let them "fix" the head gasket. Very common mis-diagnosis in cars. Why people don't check the simple stuff with an IR temp gun is beyond me.
Does it have an automatic transmission? Leaking cooler in the radiator can be a source of oil in the water.
I had a 2.3 once (single plug), that motor was bombproof.
Does it have an automatic transmission? Leaking cooler in the radiator can be a source of oil in the water.
I had a 2.3 once (single plug), that motor was bombproof.
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