454 TBI - A couple questions

[kickdeez]

Update: Just because I am a worst case scenario thinker, I decided to drain the oil to check for coolant, hoping I didn't have a head gasket leak/blowout. Oil was perfect. I put fresh oil in, a new filter, installed thermostat, 50/50 coolant/water, and buttoned everything back up. Started the truck, and temp was up to 210/220 in about 4-5 minutes of idling in the driveway. I am stumped. Fan is working, there is a fan shroud, and it is in perfect shape, thermostat is working because coolant is getting into upper hose, and it is not burning any coolant. I am at a loss. I have not messed with ignition timing at all, other than advancing/retarding the distributor to get the motor to idle about where I think it should idle. I know that's not the "right" way to do it, but it should be good enough until I can get this overheating issue figured out. Truck never overheated before. I did replace some vacuum lines with new silicone lines. I replaced them one at a time, so I am pretty sure they are all in the right spot. If someone has a picture (or multiple) of where all the vacuum lines are supposed to be routed, that may be helpful. It sounds like it is sucking in a lot more air than it used to, which leads me to believe there is a possible vacuum leak somewhere...but I sprayed a whole can of carb cleaner on all the vacuum lines, around the throttle body, and around the intake manifold yesterday, and couldn't identify a leak. If I have something in the wrong place, that could be problematic. I need some help here. I have an appointment to take the truck to a shop next week to get them to identify the cause of the overheating, as well as adjust the ignition timing, and adjust the valves. It would be nice to be able to drive the truck to the shop (without overheating) just for a tune-up, instead of having to trailer it up there for a full diagnosis.

 

[kickdeez]

And to answer your question bucket, i have not driven it yet. But the fan seems to be spinning fine. I also replaced the radiator cap, and that solved the dripping coolant issue.

 

[GTME94]

I drove my truck quite a bit this weekend and noted the following.

Stock 454 with stock oil pump. Cold oil pressure is right at 60 psi, drops down to around 45 once warm. I previously had just a mechanical gauge and it showed the same thing, these readings are from the cluster gage, I've got a new fitting that I will install so I'll have readings from both gages later this week.

Coolant temperature. Once the truck is fully warmed up, while driving, anything over idle the temp is right around 189-190. If it idles, either in park or in gear and at a traffic light or in stop/go traffic the temp goes up to the 210-220 range. The coolant temp sensor on the 454 is in the cylinder head which is the hottest part of the cooling system. Anything over idle has enough coolant flow to keep the temp down, but at idle the flow slows down enough that the temp reads higher. Keep in mind that the 220 temp isn't really over temp, most engines read the coolant temp not in the cylinder head so the "normal" temp is lower. If they had the temp sensor in the head they'd read a higher "normal" temp just like the big block.

 

[kickdeez]

GT, thanks for the response. I hear what you are saying. However, the rate at which the temp climbs is very alarming to me. There is no reason the temp should be up to 220* sitting in the driveway for 5 minutes. And I turn the truck off at that point. If I leave it on, it continues to climb (guess I should have probably mentioned that somewhere along the line).

Having, in my mind, eliminated:
-head gasket, as the oil was clean, not burning any coolant, and coolant has been tested for oil
-water pump, thermostat, and radiator, as coolant appears to be flowing through the system as it should be
-fan and shroud, as they are both present, in good shape, and the fan spins

I am left leaning towards ignition timing, or vacuum leak (or both) as being the culprit. Can somebody walk me through the process for setting the correct ignition timing (not just using the "that sounds about right" method)? I've never used a timing light before, and am just not familiar with the process.

 

[ScottyB]

It runs normal temp while driving but gets hot when idling? Sounds like a failing water pump to me. The water is still moving but not as well when the engine is running slower. I'm just a rookie so take it with a grain of sand.

 

[bucket]

Was the water pump replaced when you did the head gaskets?

 

[kickdeez]

Water pump was not replaced when I did the head gaskets. I want to say it was replaced during the motor rebuild, but I can't be sure. Correct me if I am wrong, but the water pump is a mechanical pump that is driven by the drive belt. So as long at the belt is spinning the pulley on the water pump/fan, then the water pump is going to work. My experience with water pump failures is related to the bearings. And I don't hear any bearing whine with the water pump. It is definitely pumping water through the system. I don't have any reason to believe it's not operating normally.

 

[GTME94]

GT, thanks for the response. I hear what you are saying. However, the rate at which the temp climbs is very alarming to me. There is no reason the temp should be up to 220* sitting in the driveway for 5 minutes. And I turn the truck off at that point. If I leave it on, it continues to climb (guess I should have probably mentioned that somewhere along the line).

My temp rise is fast enough that idling during a long traffic light is long enough for it to go up. I watch my gages constantly and the temp will be fine while driving, if I'm at a light and glance down it always made me panic for a second until I got used to this truck. As soon as you start to drive the temp starts to drop. Can you try holding the throttle at a little above idle to see if it goes down? Doesn't have to be much, like around a thousand rpm or so. Just enough to get the pump spinning faster and move the coolant slightly faster.

 

[kickdeez]

Yeah, if I get on the throttle it backs down a little bit, which tells me the water pump, t-stat, and fan are all working. I am just very leery of it being that warm, especially that quickly. It certainly did not get that warm sitting in the driveway before I replaced the heads. That is really my concern stems from.

 

[bucket]

Water pump was not replaced when I did the head gaskets. I want to say it was replaced during the motor rebuild, but I can't be sure. Correct me if I am wrong, but the water pump is a mechanical pump that is driven by the drive belt. So as long at the belt is spinning the pulley on the water pump/fan, then the water pump is going to work. My experience with water pump failures is related to the bearings. And I don't hear any bearing whine with the water pump. It is definitely pumping water through the system. I don't have any reason to believe it's not operating normally.

The reason I asked is because if it was replaced, you could have been sold the wrong one (flows wrong direction).

Have access to one of those infrared temp guns? It would be good to get an idea of head temp, rad temp, lower hose temp, upper hose temp, etc.

It could have air trapped somewhere still. I'd drive it and see what happens, just stay in an area that you can pull off and shut it down if needed.

 

[kickdeez]

No, i didn't change it during my work.

I am going to drive it around the neighborhood tonight and see what it does.

I may try to swing by the auto parts store and rent a timing light. Can anyone tell me what the ignition timing is supposed to be set at for these 454s?

 

[kickdeez]

Just took it for a spin around the block...

Temp hoovers around 220.

It has very little power under load. And when I try to get on it a little bit, it stumbles and I hear a fairly loud clicking noise. I have no idea what it is, but it is certainly a troubling noise.

Thoughts?

 

[bucket]

Try setting the timing at 6 degrees advanced and go from there. Clicking of an exhaust gasket maybe?

 

[kickdeez]

So I think I got some of the kinks worked out of it. I ended up advancing the timing significantly. This brought back power, got rid of the clicking/ticking and stumbling (which was actually misfiring), and it dropped the temp about 10 degrees (to about 210-215). I flushed the radiator again, and installed a 160 degree thermostat. I know that everyone has their own input on engine temps, and what they should run at. I am certainly open to hear everyone's thoughts on it, but I did it for one main reason. This truck will be used pretty much for just towing. It has a 3 speed plus low gear manual transmission and will be running fairly high RPMs on the highway with a trailer and truck behind it. I would much rather the truck run cool and burn a little more fuel, than run the risk of it getting hot when I am pulling.

Anyway, after that, it was running great, and staying around 170 degrees. So I took the truck to a local shop, and had them adjust the valves to spec (which needed to be done anyway after the top end rebuild). All the valves were apparently a little tight. I also had them put a timing light on it and set the ignition timing to factory spec which they told me was 4 degrees. Well, it ran terrible after that and was getting hot again. I took it back to them and told them to readjust it so it runs right. They said that they tweaked it several times, and finally ended up at about 12 degrees or more to get it to run right, not misfire, and not get hot. Not sure why it would run so bad being set at factory spec base timing, but it runs well where it is now. Just picked the truck up and drove it around the block a few times. The motor seems to run anywhere between 160-180 when moving. It warms up to about 200-210 when sitting idle, but quickly drops back down when I get going again. This seems to be satisfactory to me.

Just wanted to give you all the update. Feel free to comment about the thermostat and engine temps. I am curious what everyone has to say. It is not likely going to make me change my mind about the thermostat, but if there are other reasons for the motor to constantly run upwards of 210 degrees, beyond fuel mileage, I would be interested to hear them.

Thanks for all your input so far!

 

[bucket]

The outer ring on the balancer might have slipped some over time, causing the mark to be in an incorrect location. You can advance the timing more, as long as you don't get detonation on acceleration. I also think your fan clutch may be a little on the worn side and not moving quite enough air at idle.

So you have a big block Burb with a manual trans huh? That's pretty cool.