THERMOSTAT

[panchosteam]

Hi guys: I was going to change the water pump the other day because of a bad noise from the front of the engine, but when i was half way to take it off i tought a bout turning the pump by hand and checking for play on the pump or noice when you turn it or someting weird but nothing ! so i tought about checking the thermostat and i found that the litle mouse has been there!yea in the thermostat housing ,looks like some one put all kinds of glue around the thermostat to make it seal right(that's when the litle guy came in handy for them i will say...)any way i bought the new thermostat and the gasket but they sure don't look a like, the new 190 de grees from napa looks a lot different than the one that was there,the napa thermo looks like it could have a rubber gasket around it,(kind of like the ones on the 6.5's)so im curios, which one is the right thermo and why didn't the gasket from napa fited , it was paper gasket,hank you guys.
By the way this is for my 1886 6.2 CHEVY SUBURBAN 4X4

[HammerWerf]

Pancho,

It sounds from your description that the old thermostat might have been the smaller one used on the 6.5TD (RobertShaw 330-xxx). Someone tried to "glue it in" because it diddn't fit. Your '86 Suburban uses the RS 370-xxx thermostat. Larger diameter, and has no gasket around the rim. See John8662's post here

Picture of Thermostat (http://forum.thedieselpage.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=2;t=003880)

Scroll down till you see the picture.

Hope this helps.

HammerWerfer

[panchosteam]

Thank you Hammerwerf, that's the picture of the new 190* that i got from Napa auto parts,the old thermostat looks different, i was going to change the water pump, but i'll wait until tomorrow after i do the thermostat first,i started to hear a funny noise from the front of the engine so i tought about the water pump, this is a new to me 1986 k20 suburban,

[john8662]

To answer the gasket question on the thermostat, just use RTV. There is a gasket for these thermostat housings on the outlet portion covering the thermostat itself, but they will leak half of the time.

Clean the surfaces really really well, then take black or red RTV and make a solid bead around the crossover portion, then install the thermostat and then the outlet. Go ahead and tighten the bolts the required amount.

Now, for the noise on the front of your engine, I'd suspect something other than the waterpump. Because you have an 86 model 6.2, you will have the crank pulley that is also a dampner. These crank pulleys will fail because the rubber can tear or get hard and crack. So, take off your drive belts, and then grab the crank pulley and turn it by hand, see if it rotates, if so, thats probably your problem. You can also remove the 4 15mm bolts and take the crank pulley off and inspect it a little closer. When this part fails, then it will cause a knocking noise on the front of the engine.

[panchosteam]

I just measured both thermos on the gasket and they both look like same circumference,NAPA part #381-190,tant (old one stamped on it)347-180

[panchosteam]

Thank you John, i have to work on it tomorrow and inspect the mentioned items

[panchosteam]

John: you were right, the dampner is cracked so i'm shopping for it at this moment.Thank you.

[john8662]

Be sitting down when the parts guy at the dealer lets you know the price :eek:

Glad you caught the problem, these can lead to crank failure if you're not carefull.

[panchosteam]

john too bad they don't have seats at that dealer ship,and too bad they have to order it it's only $156 plus tax etc. I order it from Napa it was around $96 i bought the water pump there last week so i got credit on that and payed the difference,they said it will be there tomorrow at 8 am. so i'm happy after all, they said it comes with the harmonic balancer too.
Now should i worrie about the timing or i don't have to, will i need a pulley stractor for the harmonic balancer? and THANK YOU AGAIN FOR YOUR HELP.

[john8662]

Does the kit from Napa comes with Both the Harmonic Balancer AND the crank pulley?

Just curious, but that sounds too cheap to me, let me know what you get.

I hope you don't just get the harmonic balancer when you need the crank pulley.

"Since you're there" might as well look at the condition of the harmonic balancer. Look for cracks in the rubber (not paint over rubber) and or rubber that is squeezing out in some places and not in others, you want the rubber bead to be even.

Yes, to remove the balancer you'll need a harmonic balancer puller. You can usually rent these for cheap, or buy one for about 25.00. You will want to use your pulley bolts, and not the ones that come with the puller kit for removing the balancer.

[panchosteam]

Yes John that's what they told me that it was a two piece kit,maybe i didn't understand,but i'll let you know tomorrow again,truck is 15 min away from home and tomorrow work and after, if i get a chance swing by the suburban and see what i can do to it(about 8 pm)the lower price i got was 70... something but every body had to order it.

[mpascino]

So was that price for the pulley and balancer? I wouldn't mind replacing mine for good measure. It's the only part onthe truck that isn't new...

[panchosteam]

Hi guys,i went to NAPA the other day and they had order the HARMONIC BALANCER and not the torsional damper pulley,so i got my money back and still having fun looking for this part, i called an other dealer and they gave me a different price it was $200 and some dollars but they had to order it also, so i'll decide where i have to get this part order,i email gm parts direct and haven't got a response.