8.1L Chevy Workhorse Engine Issues

Are you loosing antifreeze along with with this. Lost power and drops of water on exhaust bolts means a blown head gasket, blown intake gasket, crack heads, Check the water when cold. If low leave cap off and run engine, if you get bubbles coming out of radiator, you have a upper engine issue. Have you taking off the dog house and looked at the engine to see if you have a water leak.

a radiator pressure tester would tell you quickly if you have a leak, and if its internal or external... after 5-10 minutes, with an external leak you will see water leaking on the ground, and if there is an internal, you will see the pressure in the radiator dropping but no drips on the ground..

this doesnt answer your power loss issue, but its part of the troubleshooting process to find out what and why..

Doing a bit of Googling I came up with a link

P1051 error code explained

The literal translation is 02 sensor low voltage.

Now... Coupled with the aroma of antifreeze I'm wondering if you do not have a heater hose or other coolant leak spraying the O2 Sensor's wires.

But the link has more info.. OH the joys of modern engines.

I get both over and under voltage on my car.

Just a note, if you have AF in your exhaust then the 02 sensors will be bad no matter how new they are.
They hate that stuff!

Thanks for all of the input. I did a search online and found that the water temp sensor could be loose. I crawled under and saw coolant on the exhaust manifold on the driver side. I tightened down the water temp sensor, 3/4 turn and I think I need to clean off the coolant from the exhaust manifold and crawl under while it is running and look for any spraying coolant. Please let me know if you have anything else that I should be checking and thanks.

Looks like coolant is coming out of the exhaust manifold and smoking where the exhaust connects. Any idea what a head gasket replacement costs on this engine?

kcgaz wrote:
Thanks for all of the input. I did a search online and found that the water temp sensor could be loose. I crawled under and saw coolant on the exhaust manifold on the driver side. I tightened down the water temp sensor, 3/4 turn and I think I need to clean off the coolant from the exhaust manifold and crawl under while it is running and look for any spraying coolant. Please let me know if you have anything else that I should be checking and thanks.

Take the doghouse off and run the engine and check it on top first. If anything on top , it going to run down. Heater hose, upper and lower radiator hose, small bypass hose, water pump. A lot of places to check on top first.

I fought the P0151 and P0152 problem for a year. I replaced the O2 sensors and that didn't help. The reason was that the O2 sensors were doing their job....signalling when the exhaust gases were incorrect.
The reason the exhaust was incorrect was that the Mass Air Flow sensor was dirty and therefore caused an incorrect mixture of fuel and air to be burned.

I would get a P0151 on every mountain I went over as I crossed Nevada into Salt Lake City. Had the MAF cleaned and the problem was instantly solved plus I had a ton of power back.

Are you using a K&N air filter? Don't. Over spraying it will cause oil to coat the MAF sensor.

I see you cleaned the MAF and so I'm a bit puzzled why that didn't help. You may need to replace it.

I've had two 8.1 engines. The first was in a 2003 GMC HD pickup. It had coolant leaks from the freeze plugs ,not the official name, and it was a known problem in the early 8.1 engine.

Another thing you need to do on a 8.1 is replace the spark plugs AND wires. All of them.

Check all of the hose clamps. mine were 1 to 2 turns loose.

... There’s a WORKHORSE Forum over at iRV2.com that’s very helpful; where I go....