Help, 4.8 taking too long to warm up

[gregory5000]

I have a 2001 GMC with the 4.8 engine. A few weeks ago I had a wreak and the front was messed up to the point the condensor coil and the radiator had to be replaced. When I got the truck back I now have a problem. It takes about 19 miles at 60 mph for the truck to get up to temp, that is alittle lower than the 210 mark on the guage. I had no problem like this before the wreak and after the wreak it was still driveable, just bent the brackets and such. I have repalced the thermostat and checked the fan clutch and all is ok. When it warming up it goes up to the first large mark on the guage and then stays there for the longest time then takes about 2 more miles to get to the normal operating temp. Any suggestions would be healpful, I am pulling out what hair I got left.

[dieselarmy13]

I know you replaced your thermostat already, but if I were you, I'd pull it out and check it. Just because it's new, doesn't mean it's good

It's hard to tell with the quality of parts nowadays.

[gregory5000]

I took and cooked the thermostats, old and the new one in a pot and they both opened within 2 sec of each other. It seems like that is the obvious thing, but this happened as soon as the radiator was replaced, no problem before. I will put a new AC one on as soon as posibble to rule that out.

[gregory5000]

MORE INFO: When I got to work this morning(27 miles), the right side of the radiator was hot that is where the top hose is. The left side(bottom hose) was very cold. The engine does not get too hot I do not think. It is looking like the new radiator is not flowing coolant thru it. What so yall think. That in advance for any suggestions.

[ed2552]

Take it back. There has to be some kind of warranty. You could take it to a radiator shop and they could probably cook it out, but if it has a warranty, just replace it. That's the problem with parts now-days, most stuff is made overseas, and poorly. That's why it's now cheaper to replace radiators than it is to have them fixed, because the replacements are cheap overseas crap.

[miracle whip]

Did you check the radiator fluid? sounds like there is not enough fluid to circulate in to the heater core! i bet they didnt burp the system. Check it when its hot!

[gregory5000]

The repair is still under warranty and I have taken it back 2 times. It is our local GMC dealer. The body shop fixed the truck, I assumed the service dept would fix the mechanical and the body shop would fix the body issues. No such luck, they are separate. We thought that it might still have air in it some where, I am going to drive it a couple of weeks and see if it gets better. Maybe get the air out if it has air in it. It is a cheap aftermarket radiator.

[bighaas79]

if they put a cheap aftermarket radiator in it after the wreck theres your problem. No brainer there. Some of the aftermarket condensors and radiators are very poorly made and do not perform like they should. Make them put a gm radiator in it. they are a dealership they should have no problem getting one. Not saying all aftermarket ones are bad but cmon, if those are the only parts they replaced it's fairly obvious they used a piece of crap.

[gregory5000]

I thought I would update everyone on this issue. I spent last winter frezzing in the truck. On the cold days 10-20 degrees, the truck would never warm up. I was about to try and get something done for this winter and 4 weeks ago I hit a deer and it took out the radiator again. I told them I would only accept a factory radiator and they agreed to only that. That fixed the issue like I knew it would. So no chinese radiators, never again.

[mikeyam187]

I don't get it, if the radiator was not flowing, the engine should have heated up faster than normal. If you were not flowing thru the heater core, then the interior heat might have not worked properly but the engine temp gauge should have still worked properly unless it had a big air gap and it was not even flowing coolant over the temp gauge.

Did you have any signs the engine was maybe overheated after you turned the engine off...like hearing the coolant boiling in the block. That is a sign of very low coolant, even if it runs almost normal temp when moving. At a high rmp, it may still flow the coolant through the engine and if it is cool outside, the engine might not overheat but at low rpm, it will not flow.

If you ran the engine without any coolant at all, the temp gauge would not even read the high block temp until it was too late. It gets its reading from the coolant itself.

[Vintage Windmills]

I don't get it either, wouldn't a bad radiator cause it to run hotter?

[primetime]

what if they bypassed the heater core all together?

[gregory5000]

It really stumped me too. i am not sure what was different about the china made radiator. It may have a the small hose that was not flowing correctly.

The engine would warm up on the gauge in the summer super fast 2-3 miles. in the winter 15-20 miles if was 20 degrees or warmer. it would never warm up under 20 degrees. Also at around 20 degrees, I could let it warm up and then put the heater fan on the highest setting and you could see the gauge go down.

The engine never showed any signs of overheating. I just got home from work in it and it now has 141K miles. It runs like a top with no problems from the radiator issue. The factory radiator fixed my problem.